Assembly and processing of procollagen type III in chick embryo blood vessels

• Published in: The Journal of biological chemistry Vol. 256; no. 5; pp. 2531 - 2537
• Main Authors: Fessler, L I, Timpl, R, Fessler, J H
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 10-03-1981
• Subjects: Animals; Chick Embryo; Kinetics; Muscle, Smooth, Vascular - metabolism; Procollagen - biosynthesis; Procollagen N-Endopeptidase - metabolism; Proline - metabolism; Protein Denaturation; Radioimmunoassay
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)69815-7

The processing of [3H]proline-labeled procollagen III in excised chick embryo blood vessels was found to differ significantly
from that of procollagen I in the same tissue. While first the amino propeptides and then the carboxyl propeptides were fairly
rapidly cleaved from procollagen I, only the carboxyl propeptides were split off procollagen III, leaving pN-collagen III.
This intermediate, which is only slowly converted to collagen III by loss of amino propeptides, was characterized by its sedimentation
properties, isolation of the amino propeptide, and reaction with purified antibodies that are specific against bovine amino
propeptide III. It is interchain disulfide-linked, both through the amino propeptide and the carboxyl ends of the collagen
chains. The conversion of procollagen III to pN-collagen III either in blood vessels, or after isolation by a carboxyl procollagen
peptidase obtained from chick tendon fibroblast cultures, is inhibited by 50 mM arginine. Underhydroxylated procollagen III
was isolated from blood vessels treated with alpha, alpha'-dipyridyl. Its amino propeptides reacted with the above antibodies
but were not linked to each other. In contrast, its carboxyl propeptides were interchain disulfide-bridged, supporting previous
suggestions that the carboxyl propeptides play a role in the assembly of procollagen trimer.