Transforming growth factor beta isoform 2-specific high affinity binding to native alpha 2-macroglobulin. Chimeras identify a sequence that determines affinity for native but not activated alpha 2-macroglobulin.

摘要: Transforming growth factor beta 2 (TGF-beta 2) is less potent than TGF-beta 1 in some endothelial cell proliferation assays due to the greater tendency of bind alpha 2-macroglobulin (alpha 2M). Substitution residues 40-47 into sequence yields a chimeric molecule that, like 1, expresses activity that not substantially affected by serum 2M (Burmester, J. K., Qian, S. W., Roberts, A. B., Huang, A., Amatayakul-Chantler, S., Suardet, L., Odartchenko, N., Madri, and Sporn, M. B. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 8628-8632). In this investigation, we studied binding chimeras, which contain 40-47, both major conformations human under apparent equilibrium conditions. Native 2M, primary form protein serum, bound 2/beta (40-82) (40-47) with low affinity. The KD values for two chimeras native were 310 330 nM, respectively. These much higher determined (11 nM) equivalent 2M. By contrast, 2M-methylamine, an altered conformation high affinity (16 19 nM), characteristic 1. Fetal bovine heart DNA synthesis was inhibited similar degree 2, (40-82), presence dilute (0.2%) fetal serum. When 0.07 microM 2M-methylamine added, activities significantly counteracted while unchanged, as would be predicted analyses. studies indicate structural elements, mediate conformationally transformed are equivalent. Residues critical determining but important 2M-methylamine.