J. Biol. Chem., Vol. 261, Issue 25, 11600-11607, 09, 1986
Bovine brain-derived growth factor. Purification and characterization of its interaction with responsive cells
JS Huang, SS Huang and MD Kuo
A large-scale purification procedure for brain-derived growth factors,
without chromatography in 0.1% trifluoracetic acid, has been developed. Two
related brain-derived growth factors have been purified to homogeneity from
bovine brain using this procedure involving ammonium sulfate fractionation,
followed by chromatography on CM-Sephadex C-50, sulfated Sephadex G-50, and
heparin-Sepharose 4B. Brain-derived growth factor A (BDGF-A, molecular
weight approximately 16,000) and brain- derived growth factor B (BDGF-B,
molecular weight approximately 17,000) were eluted from heparin-Sepharose
4B at 1.2 and 1.6 M NaCl, respectively. Both BDGF-A and BDGF-B have a pI
value of 5.7, have the same specific mitogenic activity, and react with
mouse anti-BDGF-A antiserum. Both growth factors have a broad spectrum of
mitogenic activity (vascular and aorta endothelial cells, chondrocytes,
osteoblasts, epithelial cells, glial cells, fibroblasts, and smooth muscle
cells), with a half-maximum effect at 10-20 pM. The binding of BDGF to
bovine aorta endothelial cells and Swiss mouse 3T3 cells has been
characterized. Binding of 125I-BDGF-A to these cells reached equilibrium in
less than 15 min. Scatchard plot analysis of the binding of 125I-BDGF-A to
endothelial cells and 3T3 cells showed a single class of high-affinity
receptor with Kd values of 20 +/- 5 and 13 +/- 3 pM and receptor
numbers/cell of 7,000 +/- 1,000 and 20,000 +/- 3,000, respectively. BDGF-B
competed for 125I-BDGF-A binding in the same manner as unlabeled BDGF-A,
suggesting that BDGF-A and BDGF-B bind to the same receptor. Basic
pituitary fibroblast growth factor appeared to be a weak inhibitor, whereas
platelet-derived growth factor and epidermal growth factor had no effect on
125I-BDGF-A binding. Protamine, histone, polylysine, and polyarginine are
potent inhibitors of the mitogenic activity of BDGF-A and BDGF-B and of
binding of 125I- BDGF-A to responsive cells. The half-time (t1/2) of
internalization and degradation of cell surface-bound 125I-BDGF is 3 h.