Cathepsin D-mediated processing of procollagen: lysosomal enzyme involvement in secretory processing of procollagen.
The proteolytic removal of the extension COOH-terminal propeptide from procollagen has been examined in vitro. A crude enzyme activity was identified in a whole-chicken-embryo extract that acted at acid pH and appeared to be similar to one identified previously [Davidson, J. M., McEneany , L. S. G. & Bornstein , P. (1979) Eur. J. Biochem. 100, 551-558]. This activity was inhibitable by pepstatin but not by leupeptin, suggesting that it might be cathepsin D. Cathepsin D was purified 907-fold from chicken livers by affinity chromatography on pepstatin-aminohexyl-Sepharose 4B and was found to remove the COOH propeptides from procollagen. At pH 6.0, the site of cleavage appeared to shift from the COOH telopeptide to the COOH telopeptide/propeptide junction, based upon the difference in electrophoretic migration of the cleavage products, although determining the actual cleavage site will require end-group analysis. A model for the involvement of cathepsin D in the in vivo processing of procollagen is presented.
D000595:Amino Acid Sequence; D000818:Animals; D002402:Cathepsin D; D002403:Cathepsins / Q000378:metabolism*; D002478:Cells, Cultured; D002642:Chick Embryo; D004705:Endocytosis; D006863:Hydrogen-Ion Concentration; D008247:Lysosomes / Q000502:physiology*; D011347:Procollagen / Q000378:metabolism*; D011499:Protein Processing, Post-Translational
D011347:Procollagen; D002403:Cathepsins; D002402:Cathepsin D