HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 275, Issue 50, 38961-38964, December 15, 2000

This Article Abstract Full Text (PDF) All Versions of this Article: 275/50/38961    most recent C000604200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hou, Y. Articles by Gautam, N. Search for Related Content PubMed PubMed Citation Articles by Hou, Y. Articles by Gautam, N. Social Bookmarking                      What's this?

ACCELERATED PUBLICATION
Selective Role of G Protein  Subunits in Receptor Interaction^*

Yongmin Hou, Inaki Azpiazu, Alan Smrcka^§, and N. Gautam^¶

From the  Departments of Anesthesiology and ^¶ Genetics, Washington University School of Medicine, St. Louis, Missouri 63110 and the ^§ Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642

Received for publication, September 1, 2000, and in revised form, October 2, 2000

	ABSTRACT

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS AND DISCUSSION REFERENCES

Receptor stimulation of nucleotide exchange in a heterotrimeric G protein () is the primary event-modulating signaling by G proteins. The molecular mechanisms at the basis of this event and the role of the G protein subunits, especially the complex, in receptor activation are unclear. In a reconstituted system, a purified muscarinic receptor, M2, activates G protein heterotrimers i215 and i217 with equal efficacy. However, when the  subunit type is substituted with o, o17 shows a 100% increase in M2-stimulated GTP hydrolysis compared with o15. Using a sensitive assay based on complex stimulation of phospholipase C activity, we show that both 15 and 17 form heterotrimers equally well with o and i. These results indicate that the  subunit interaction with a receptor is critical for modulating nucleotide exchange and is influenced by the subunit-type composition of the heterotrimer.

	INTRODUCTION

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS AND DISCUSSION REFERENCES

The G protein cycle is primarily regulated by the interaction of heterotrimeric G protein and cell surface receptors. Both  and subunits are required for interaction with receptor (1-3). The G protein  subunit has been demonstrated to interact with and selectively couple to receptors, especially muscarinic receptors (4). The role of the complex in interaction with the receptor is, however, less well understood. There is evidence for interaction of the G protein  subunit with receptors (5). There are also indications for specificity in this interaction. Results from experiments in pituitary GH3 cells using antisense oligonucleotides specific to different  or  subunit types indicated that signaling stimulated by different receptors can be specifically inhibited (6). The 1 subunit type allowed effective coupling of Gt with rhodopsin in contrast to 2 and 3 (7). In superior cervical ganglion (SCG)¹ neurons peptides specific to the 5 subunit type disrupted signaling from the M2/M4 muscarinic receptors, whereas peptides specific to 7 and 12 had no effect (8). Because this implied that the M2 muscarinic receptor selectively interacts with a G protein containing 5 but not 7, we tested the ability of the M2 receptor to activate G proteins containing these two subunits. Earlier studies addressing the question of G protein specificity for receptors used whole cells or crude membranes from cells. Experiments with intact cells do not definitively allow identification of the site at which the disruption in signaling occurs. Crude membranes contain endogenous G proteins, receptors, and other components that may affect analysis of specificity in receptor-G protein interactions. To more rigorously and directly examine the effect of G protein subunit constitution on receptor-G protein coupling, we reconstituted a purified muscarinic receptor, M2, in lipids and measured its ability to activate G proteins containing different  subunits. The M2 receptor is known to couple to members of the Gi/o family but not Gq (9). To examine whether the subunit-type constitution of a heterotrimer influenced receptor interaction we tested different combinations of the  and  subunit types o5, o17, i215, and i217. Recombinant G protein subunits were purified from insect cells, and heterotrimers constituting different combinations of  and  subunits were assembled. We measured M2-stimulated GTPS binding and GTPase activity using defined G protein heterotrimers. GTPS binding assays were performed at a ratio of the G protein  subunit to receptor of 100:1 (1 nM receptor). Because subtle differences in receptor activation could be missed under these conditions, we developed GTPase assays to measure receptor activation of a G protein at a ratio of G protein to receptor approaching 1:1 (1 nM receptor). These assays detected consistent and significant differences in the ability of the M2 receptor to activate o15 compared with o17. In contrast, when the  subunit type was substituted with i2 there was no difference in receptor-stimulated GTPase activity between i215 and i217. The difference in receptor-stimulated activity between o15 and o17 could be due to differential heterotrimer formation between o and these complexes. To test this possibility we developed a novel phospholipase C (PLC)-based assay to measure heterotrimer formation. This assay indicated that the differences in GTPase activity between o5 and o7 arose as a result of differential receptor coupling rather than differential heterotrimer formation.

	EXPERIMENTAL PROCEDURES

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS AND DISCUSSION REFERENCES

Expression and Purification of Recombinant G Protein Subunits-- G protein subunits were expressed in the baculovirus Sf9 cell system. The purification was essentially performed according to the procedures described before (10). The purity and quantity of these proteins were assessed by separating by SDS gel electrophoresis, staining with Coomassie Blue, scanning with a laser densitometer, and comparing with protein standards. G proteins o and i2 were purified from Escherichia coli using published methods (11). RGS4 was a gift from Dr. M. Linder, Washington University.

Measuring PLC Activity-- The -stimulated PLC assay was performed using a procedure as stated previously (12).

Purification, Reconstitution, and Functional Characterization of Recombinant M2-- His-tagged M2 was expressed in Sf9 cells and purified using a CoCl₂ affinity column (13). Purified M2 was reconstituted into brain lipids (Folch type VII; Sigma) and characterized by binding to antagonist, [³H]N-[³H]methylscopolamine (NMS). The receptor (50 pM) was incubated with various concentrations of [³H]NMS at room temperature for 60 min in a binding buffer containing 20 mM sodium phosphate (pH 7.4) and 10 mM MgCl₂. The reactions were terminated by filtration through Whatman GF/B membranes, and the filters were then washed with ice-cold binding buffer before counting the radioactivity.

GTPS Binding and GTP Hydrolysis-- The formation of heterotrimeric Go protein, the M2-G protein complex, GTPS binding, and GTP hydrolysis assays are described in the legends for Figs. 2 and 3.

Measuring Heterotrimer Formation-- To form the G protein heterotrimer, 360 nM complex was initially incubated with increasing concentrations of  subunit in ice for 30 min to obtain a wide range of : ratios in a buffer containing 20 mM Hepes (pH 8.0), 100 mM NaCl, 2 mM MgCl₂, 0.1 mM EDTA, 1 mM DTT, and 0.5 mg/ml BSA. This mixture was then diluted 10-fold in a buffer containing 50 mM Hepes (pH 7.2), 3 mM EGTA, 1 mM EDTA, 5 mM MgCl₂, 100 mM NaCl, and 1 mM DTT. 10 µl of these diluted samples containing and various concentrations of  subunit was then added to 50 µl of PLC reaction buffer containing [³H]PIP₂ substrate and PLC 3 for determining enzyme activity as described above.

	RESULTS AND DISCUSSION

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS AND DISCUSSION REFERENCES

Purification and Functional Characterization of Recombinant G Protein Subunits and M2-- complexes purified as described above were over 95% pure (Fig. 1A). When PLC 3 isozyme stimulation by 15 or 17 complexes was measured, the similar levels of activation of PLC by both complexes indicated that the functional proportion of each complex was the same (Fig. 1B). In addition, we ensured that the concentration of detergent in the purified 15 and 17 samples were identical, using thin layer chromatography and detergents at various concentrations as standards (data not shown). His-M2 has been shown to possess similar properties to native M2 after reconstitution into lipids (13). His-M2 receptor was purified as described earlier. The purified M2 was ~90% pure as assessed by the methods used to quantify the G protein subunits. Reconstituted M2 had a K_d for an antagonist, NMS, similar to native M2 (14) (Fig. 1C).

View larger version (28K): [in this window] [in a new window]   Fig. 1.   Characterization of purified recombinant M2 receptor and G protein subunits. A, G protein 15 and 17 subunits purified from insect cells were separated by SDS gel electrophoresis and stained with Coomassie Blue. B, purified 15 and 17 stimulate similar levels of PLC 3 activity. Indicated concentrations of 15 or 17 were incubated with a buffer containing [3H]PIP2, PLC 3 for 15 min at 30 °C. [3H]IP3 production was measured by scintillation counting. Representative results were from three independent experiments. C, [3H]NMS binding to reconstituted M2. His-M2 was purified and reconstituted as described earlier. The reconstituted receptor was bound to various concentrations of [3H]NMS. Specific binding of [3H]NMS was determined from the difference between [3H]NMS bound in the absence and presence of an antagonist, 10 µM atropine. The saturation curve and Scatchard plot (inset) were generated by using nonlinear and linear regression (SigmaPlot). Kd of M2 for NMS was calculated to be 0.25 ± 0.06 nM, similar to that of native M2 as reported previously. The experiment was performed twice.

M2-stimulated GTPS Binding to Go Containing 5 or 7-- To allow for accurate titration of various concentrations of G protein subunits with purified receptor, we developed a system in which receptor alone was first reconstituted into lipids, quantified, and then assayed for its ability to activate varying concentrations of added G protein (Fig. 2, see legend). o was assayed in the presence of two different complexes, 15 and 17. The reconstituted M2 efficiently activates o in a -dependent manner (Fig. 2A). At an ::M2 ratio of 100:10:1 with 1 nM M2, no differences were noted in the ability of M2 to activate o15 and o17 (Fig. 2A). It was possible that at lower concentrations of o and an :M2 ratio closer to 1:1, subtle differences would be detected. However, GTPS binding at lower concentrations of o (e.g. 10 nM) was not sufficiently above background for use in these assays. Given this constraint, it was possible only to examine the effect of varying concentrations of complex, as well as agonist, on M2-stimulated GTPS binding to o15 and o17. These assays did not reveal any differences between the heterotrimers (Fig. 2, B and C). complex concentrations below 10 nM could not be examined because of the low activity detected above background.

View larger version (15K): [in this window] [in a new window]   Fig. 2.   M2-stimulated GTPS binding to Go. A, time course experiments for M2-activated GTPS binding to Go at the ::M2 ratio of 100:10:1. B, comparison of M2-stimulated GTPS binding to Go containing 5 and 7 using different ratios of : as indicated. C, M2-stimulated GTPS binding to o15 and o17 in the presence of varying concentrations of agonist, carbachol, at an ::M2 ratio of 100:10:1. Heterotrimeric G protein subunits were formed by incubating  and subunits in ice for 30 min in a buffer containing 25 mM Hepes, 100 mM NaCl, 2 mM MgCl2, 0.1 mM EDTA, 10 µM GDP, and 1 mM DTT. Reconstituted M2 was then added and incubated for an additional 30 min. The M2-G protein complex was incubated at room temperature with 0.2 µM [35S]GTPS and carbachol or water (control). In A, incubation was performed at different time points, whereas reactions were carried out for a fixed time (4 min) in B and C. The samples were filtered through nitrocellulose membranes, and bound [35S]GTPS was detected by scintillation counting. The results are representative of three independent experiments.

Go but Not Gi Containing Different  Subunits Shows Differences in M2-stimulated GTPase Rates-- The M2-promoted GTPS binding assay could mask differential activation of heterotrimers containing different  subunits for the following two related reasons: (i) the excess of  subunit relative to receptor (100:1) present in the GTPS assay and (ii) the lack of amplification in the signal, because an  subunit bound to the nonhydrolyzable GTPS analog undergoes only one cycle of activation unlike GTP-bound  subunit. We therefore examined M2-activated GTP hydrolysis by defined Go/i protein heterotrimers. M2 stimulation with carbachol increased GTPase activity 5-10-fold over the activity in the absence of agonist. The addition of RGS4, a GTPase-activating protein for the Go/i family (15), promoted an additional 10-fold increase in GTPase activity (data not shown). This increase in sensitivity allowed us to measure G protein activation at ratios of  to receptor close to 1:1 with a constant concentration of 1 nM M2. When defined heterotrimers were assayed under these conditions, the receptor-stimulated GTPase activity of o17 was 100% higher than o15 (see Fig. 3A and Table I). This difference was seen at all G protein concentrations tested (Table I). The difference was also seen with 15 and 17 preparations purified independently indicating that the difference was not because of contaminants in one particular preparation of the complexes. Statistical analysis using the Student's t test showed that the differences are significant (p < 0.05). To test whether the  subunit type in the heterotrimer influenced this differential activity, we compared the receptor-stimulated GTPase activity of i215 and i217. Surprisingly, there was no difference in GTPase activity between the two heterotrimers at various ratios of Gi2:M2 (see Fig. 3B and Table I).

View larger version (20K): [in this window] [in a new window]   Fig. 3.   M2-stimulated GTP hydrolysis by Go and Gi containing 5 and 7. A, o15 shows a 100% increase in M2-activated GTP hydrolysis relative to o17. The increases in GTPase activity at all time points at both 2 nM and 4 nM concentrations are statistically significant (p < 0.05). B, i215 and i217 have the same level of M2-stimulated GTPase activity. The formation of heterotrimer was as in the GTPS binding assay. Reconstituted M2 and RGS4 proteins were incubated with heterotrimeric Go in ice for 30 min. The receptor-G protein complex was then mixed with carbachol or water before [-32P]GTP was added to initiate the reaction at 25 °C. A typical reaction mixture contained differing concentrations of G protein, 1 nM receptor, 0.1 µM RGS4, 0.2 µM [-32P]GTP, 5 µM GDP, and 1 mM carbachol in a buffer of 20 mM Hepes (pH 8.0), 100 mM NaCl, 2 mM MgCl2, 0.1 mM EDTA, 1 mM DTT, and 0.5 mg/ml BSA. Activity measured in the presence of 200 µM GTP (1000 times more than radiolabeled GTP) served as a control for nonspecific activity. Aliquots were taken at indicated time points and quenched in 0.5 ml of ice-cold buffer containing 5% activated charcoal and 50 mM K3PO4. Samples were centrifuged, and supernatants were quantified by scintillation counting. Experiments have been repeated at least five times, and representative data are shown.

View this table: [in this window] [in a new window]   Table I M2-promoted GTPase activity of Go and Gi containing 5 and 7

The 15 and 17 Subunits Form Heterotrimers Equally Well with o or i2-- Formation of the heterotrimer is essential for G protein interaction with a receptor (3) (Fig. 2). One explanation for the difference in the receptor-stimulated GTPase activity between o15 and o17 could be differential efficacy of heterotrimer formation between 15 and 17 with o. To test this possibility, we developed an assay for measuring G protein heterotrimer formation. Thus far, efficacy of heterotrimer formation has been measured using pertussis toxin-mediated ADP ribosylation of the  subunit, which is enhanced by the complex. However, the mechanistic basis for complex requirement in this assay is unclear. Also, the enhancement by the complex is catalytic and requires relatively high concentrations of the subunits (>1 µM) inappropriate for measuring heterotrimer formation under conditions identical to the GTPase assays used here (<10 nM subunits). To overcome these problems we developed an alternative approach. This approach was based on the idea that the complex contains overlapping binding sites for both the  subunit and PLC 3 (16). Thus, binding of i/o to complex would prevent interaction with PLC 3. Heterotrimer formation should thus lead to inhibition of -stimulated PLC activity. As shown in Fig. 4, this assay is highly sensitive. -stimulated PLC activity is inhibited by the addition of o or i subunit. Inhibition is dependent on the concentration of  subunit added. The assay is sensitive in the nM range of  and subunits. Both 15 and 17 form a heterotrimer with o and i2 equally well (Fig. 4, A and B).

View larger version (15K): [in this window] [in a new window]   Fig. 4.   The 15 and 17 subunits form heterotrimers equally well with o and i2. 15 and 17 were incubated with varying concentrations of o (A) and i2 subunit (B). The heterotrimer formation between and increasing concentrations of  subunit is described under "Experimental Procedures." PLC 3 activity stimulated by was measured to monitor heterotrimer formation. The activity stimulated by free serves as a positive control representing maximum PLC activity (100%), whereas the enzyme activity stimulated by o subunit alone was the negative control. PLC activity was assayed according to the legend for Fig. 1. Experiments have been repeated at least three times, and representative results are shown.

G Protein  and  Subunit Interaction with Receptor-- Indications that the  subunits may impart specificity to receptor-G protein interaction have come from the analysis of different receptors (7, 8, 17, 18). In studies with the muscarinic receptor, a peptide specific to the C terminus of the 5 subunit was shown to inhibit coupling of G protein to the M2 receptor and also disrupt a muscarinic receptor (M2/M4)-mediated signaling pathway in SCG neurons (8). In comparison, a homologous peptide from 7 was ineffective indicating that the 5 subunit interacted with the M2/M4 class of receptors, whereas 7 did not. To test whether the results of the peptide activity in intact cells could be reproduced in a reconstituted system, we expressed, purified, and assayed the ability of G proteins containing the same  subunit types to functionally couple to the purified M2 muscarinic receptor. By using a sensitive functional assay we sought to elucidate the underlying mechanistic bases for any differences in coupling. The results show a clear difference in the ability of o heterotrimers containing 5 or 7 to be activated by M2 receptors. o17 has a distinctly higher GTP hydrolysis rate compared with o15. A simple interpretation of this would be that o17 couples more efficiently with M2 than o15. However, we favor an alternative interpretation in the context of earlier experiments, which indicate that the C terminus of the 5 subunit more effectively interacts with M2 than 7 (8). Because 15 and 17 interact equally well with o, the difference in GTPase activity has to arise from a difference in the rate of receptor-stimulated nucleotide exchange between the two heterotrimers. It is likely that the 5 subunit interacts appropriately with the M2 receptor, whereas 7 does not, and the increased GTPase activity is a consequence of more rapid "leaky" nucleotide exchange from the resulting inappropriate configuration of the o subunit with reference to the 17 complex. This interpretation is consistent with a previous conclusion that the complex plays a direct or indirect role at the receptor surface in controlling nucleotide exchange in the  subunit (19).

Strikingly, the difference seen between o17 and o15 disappears when o is substituted with i2. One possibility is that i2 interacts with a different site on the receptor compared with o thus changing the overall conformation of the G protein heterotrimer at the receptor surface. There are evidences from the analyses of different receptors for such differential interaction with G protein subtypes (20). The distinctly differential rate of M2-induced Go and Gi GTPase rates (Fig. 3), as well as GTPS binding (21), are also consistent with this scenario. Regardless of the mechanism, this result indicates that the heterotrimer composition influences receptor-stimulated nucleotide exchange.

Because the G protein subunits are families of proteins it has been thought that particular combinations of  and subtypes may differentially regulate signaling (22). The results here indicate that different  subunit and  subunit types, through specific interactions with a receptor, can coordinately modulate receptor-stimulated nucleotide exchange resulting in differential signaling kinetics.

	ACKNOWLEDGEMENTS

We thank Vanessa Chang in our laboratory for discussions and assistance with PLC 3 assays. We thank Dr. M. Linder for RGS4 protein, Dr. T. Kozasa for 1 and o baculoviruses, and Dr. E. Ross for His-M2 baculovirus.

	FOOTNOTES

^* This work was supported by National Institutes of Health Grants GM53536 (to A. S.) and GM46963 (to N. G.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

To whom correspondence should be addressed: Box 8054, Washington University School of Medicine, St. Louis, MO 63110. Tel.: 314-362-8568; E-mail: gautam@morpheus.wustl.edu.

Published, JBC Papers in Press, October 19, 2000, DOI 10.1074/jbc.C000604200

	ABBREVIATIONS

The abbreviations used are: SCG, superior cervical ganglion; PLC, phospholipase C; NMS, N-methylscopolamine; GTPS, guanosine 5'-3-O-(thio)triphosphate; BSA, bovine serum albumin; PIP₂, phosphatidylinositol-4,5-biphosphate; DTT, dithiothreitol; IP₃, inositol 1,4,5- trisphosphate.

	REFERENCES

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS AND DISCUSSION REFERENCES

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				D. K. Saini, V. Kalyanaraman, M. Chisari, and N. Gautam A Family of G Protein beta{gamma} Subunits Translocate Reversibly from the Plasma Membrane to Endomembranes on Receptor Activation J. Biol. Chem., August 17, 2007; 282(33): 24099 - 24108. [Abstract] [Full Text] [PDF]

				C. A. Johnston and D. P. Siderovski Receptor-Mediated Activation of Heterotrimeric G-Proteins: Current Structural Insights Mol. Pharmacol., August 1, 2007; 72(2): 219 - 230. [Abstract] [Full Text] [PDF]

				Y. Trusov, J. E. Rookes, K. Tilbrook, D. Chakravorty, M. G. Mason, D. Anderson, J.-G. Chen, A. M. Jones, and J. R. Botella Heterotrimeric G Protein {gamma} Subunits Provide Functional Selectivity in G{beta}{gamma} Dimer Signaling in Arabidopsis PLANT CELL, April 1, 2007; 19(4): 1235 - 1250. [Abstract] [Full Text] [PDF]

				S. M. Mervine, E. A. Yost, J. L. Sabo, T. R. Hynes, and C. H. Berlot Analysis of G Protein beta{gamma} Dimer Formation in Live Cells Using Multicolor Bimolecular Fluorescence Complementation Demonstrates Preferences of beta1 for Particular {gamma} Subunits Mol. Pharmacol., July 1, 2006; 70(1): 194 - 205. [Abstract] [Full Text] [PDF]

				C.-S. Myung, W. K. Lim, J. M. DeFilippo, H. Yasuda, R. R. Neubig, and J. C. Garrison Regions in the G Protein {gamma} Subunit Important for Interaction with Receptors and Effectors Mol. Pharmacol., March 1, 2006; 69(3): 877 - 887. [Abstract] [Full Text] [PDF]

				S. K. Gibson and A. G. Gilman Gi{alpha} and G{beta} subunits both define selectivity of G protein activation by {alpha}2-adrenergic receptors PNAS, January 3, 2006; 103(1): 212 - 217. [Abstract] [Full Text] [PDF]

				K. R. Kerchner, R. L. Clay, G. McCleery, N. Watson, W. E. McIntire, C.-S. Myung, and J. C. Garrison Differential Sensitivity of Phosphatidylinositol 3-Kinase p110{gamma} to Isoforms of G Protein {beta}{gamma} Dimers J. Biol. Chem., October 22, 2004; 279(43): 44554 - 44562. [Abstract] [Full Text] [PDF]

				T. R. Hynes, S. M. Mervine, E. A. Yost, J. L. Sabo, and C. H. Berlot Live Cell Imaging of Gs and the {beta}2-Adrenergic Receptor Demonstrates That Both {alpha}s and {beta}1{gamma}7 Internalize upon Stimulation and Exhibit Similar Trafficking Patterns That Differ from That of the {beta}2-Adrenergic Receptor J. Biol. Chem., October 15, 2004; 279(42): 44101 - 44112. [Abstract] [Full Text] [PDF]

				T. R. Hynes, L. Tang, S. M. Mervine, J. L. Sabo, E. A. Yost, P. N. Devreotes, and C. H. Berlot Visualization of G Protein {beta}{gamma} Dimers Using Bimolecular Fluorescence Complementation Demonstrates Roles for Both {beta} and {gamma} in Subcellular Targeting J. Biol. Chem., July 16, 2004; 279(29): 30279 - 30286. [Abstract] [Full Text] [PDF]

				S. L. Chinault and K. J. Blumer The C-terminal Tail Preceding the CAAX Box of a Yeast G Protein {gamma} Subunit Is Dispensable for Receptor-mediated G Protein Activation in Vivo J. Biol. Chem., May 30, 2003; 278(23): 20638 - 20644. [Abstract] [Full Text] [PDF]

				W. F. Schwindinger, K. S. Betz, K. E. Giger, A. Sabol, S. K. Bronson, and J. D. Robishaw Loss of G Protein gamma 7 Alters Behavior and Reduces Striatal alpha olf Level and cAMP Production J. Biol. Chem., February 14, 2003; 278(8): 6575 - 6579. [Abstract] [Full Text] [PDF]

				J. E. Dumont, S. Dremier, I. Pirson, and C. Maenhaut Cross signaling, cell specificity, and physiology Am J Physiol Cell Physiol, July 1, 2002; 283(1): C2 - C28. [Abstract] [Full Text] [PDF]

				X. Jian, W. A. Clark, J. Kowalak, S. P. Markey, W. F. Simonds, and J. K. Northup Gbeta gamma Affinity for Bovine Rhodopsin Is Determined by the Carboxyl-terminal Sequences of the gamma Subunit J. Biol. Chem., December 14, 2001; 276(51): 48518 - 48525. [Abstract] [Full Text] [PDF]

				I. Azpiazu and N. Gautam G Protein gamma Subunit Interaction with a Receptor Regulates Receptor-stimulated Nucleotide Exchange J. Biol. Chem., November 2, 2001; 276(45): 41742 - 41747. [Abstract] [Full Text] [PDF]

				Y. Hou, V. Chang, A. B. Capper, R. Taussig, and N. Gautam G Protein beta Subunit Types Differentially Interact with a Muscarinic Receptor but Not Adenylyl Cyclase Type II or Phospholipase C-beta 2/3 J. Biol. Chem., June 1, 2001; 276(23): 19982 - 19988. [Abstract] [Full Text] [PDF]

				D. S. Evanko, M. M. Thiyagarajan, D. P. Siderovski, and P. B. Wedegaertner Gbeta gamma Isoforms Selectively Rescue Plasma Membrane Localization and Palmitoylation of Mutant Galpha s and Galpha q J. Biol. Chem., June 22, 2001; 276(26): 23945 - 23953. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF)