A role of the latent TGF-beta 1-binding protein in the assembly and secretion of TGF-beta 1.

摘要: Abstract Transforming growth factor-beta 1 (TGF-beta 1) is synthesized as latent complexes with high molecular weights. The large complex of TGF-beta in platelets composed three components, i.e. the mature 1, which non-covalently associated a disulphide-bonded N-terminal remnant precursor 1-latency peptide) and binding protein (LTBP). peptide sufficient for latency whereas functions LTBP remain to be elucidated. In human erythroleukemia cell line, HEL, production form was induced more than 100-fold by phorbol 12-myristate 13-acetate. Analysis Northern blotting revealed that both were coordinated fashion. immunoprecipitation using antibodies against dimer has size 205 kd under reducing conditions this type, similar from cells transfected cDNA LTBP, but larger platelet (125-160 kd). Limited tryptic digestion HEL analysis SDS-PAGE showed bands sizes those suggesting difference involves cell-specific processing. biosynthesis studied pulse-chase analysis. became covalently within 15 min after synthesis line. Secretion observed early 30 LTBP; at same time, free not bound seen. contrast, remained inside an unprocessed longer time period without secreted only very slowly. Furthermore, results partial molecule suggested it contained improper disulphide bonding. These suggest plays critical role assembly secretion 1.