J. Biol. Chem., Vol. 261, Issue 15, 6912-6918, May, 1986
Interaction of the cytoskeletal component vinculin with bilayer structures analyzed with a photoactivatable phospholipid
V Niggli, DP Dimitrov, J Brunner and MM Burger
The cytoskeletal component vinculin has been proposed to act as an
actin-plasma membrane linker. In order to demonstrate a possible direct
interaction of vinculin with bilayers, photolabeling with a phospholipid
generating a highly reactive carbene was used. This phosphatidylcholine
analogue (1-palmitoyl-2-[10-[4- [(trifluoromethyl)diazirinyl]phenyl]-[3H]
9-oxaundecanoyl]-sn-glycero-3- phosphocholine), with the photoactivatable
diazirine group on its apolar portion, has been shown to label selectively
membrane-embedded domains of membrane proteins. Vinculin is significantly
labeled upon incubation and photolysis with liposomes containing trace
amounts of this photoactivatable phospholipid, but only when the liposomes
also contain acidic phospholipids. Labeling of vinculin is markedly
increased (5-17-fold) by all acidic phospholipids tested so far (30%, w/w),
compared to labeling in neutral phospholipids. Labeling is high at low
ionic strength, but significant vinculin labeling can still be observed at
physiological salt concentrations and acidic phospholipid content of the
membrane. Our results provide evidence that vinculin inserts into the
hydrophobic part of the bilayer by interacting with acidic phospholipids. A
similar interaction may be of importance in vivo.