Structural studies on rat prostatic binding protein. The primary structure of component C1 from subunit F.

The amino acid sequence of component C1, the polypeptide specific for subunit F of prostatic binding protein, the major secretory glycoprotein of the rat ventral prostate, has been determined. Its structure was established using the manual Edman degradation on the intact protein and on the most relevant fragments isolated from trypsin, chymotrypsin, thermolysin and Staphylococcus aureus protease digests of the 14C-labelled S-carboxamidomethylated component C1. Component C1 contains 88 amino acids corresponding to a molecular weight of 10246. It is an acidic polypeptide due to the presence of 17 acidic residues; its three cysteine residues are almost symmetrically distributed over the peptide chain. Highly polar regions are found in positions 17-27 and 37-47, while the C-terminal part of the molecule contains two hydrophobic segments.