Procollagen III C-Terminal Propeptide (PIIICP)

PIIICP occurs as a trimer consisting of three identical monomeric PIIICP subunits that are linked by intermolecular disulfide bridges. Structural considerations and site-directed mutagenesis experiments with a collagen minigene have led to the conclusion that at least 4 and probably 6 cysteine residues are involved in intramolecular disulfide bridge formation and that only cysteines 51 and 68 are involved in intermolecular disulfide bridge formation. It has been observed, however, that the region around this intermolecular cystine bridge is critical for the correct formation of intramolecular disulfide bridges and that a Cys->Ser mutation in that region also leads to impaired intramolecular disulfide bridge formation. The PIIICP cDNA sequence has been published and two entries are found in the Genbank data base. The sequence was identical to the sequence published by Ala-Kokko et al., 1989, and deviated from the sequence published by Loidl et al. (1984) in one amino acid.