Putative convertase involved in the proteolytic conversion of rat proalbumin to serum albumin.
We have found a proteolytic activity in Golgi membranes which efficiently converts [35S]methionine-labeled proalbumin, isolated from pulse-labeled rat hepatocytes in culture, to serum albumin in an in vitro assay system. The proalbumin-converting activity was dependent on Ca2+ and the maximum activity was observed at pH 5.5-6.0. Since the enzyme activity was found to be resistant not only to both leupeptin and E-64 but also to thiol-blocking reagents, it is unlikely that cathepsin B is involved in the proteolytic conversion of proalbumin occurring in the Golgi complex.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D006056:Golgi Apparatus / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D010447:Peptide Hydrolases / Q000502:physiology*; D011228:Prealbumin / Q000378:metabolism*; D051381:Rats; D012709:Serum Albumin / Q000378:metabolism*
D011228:Prealbumin; D012709:Serum Albumin; D010447:Peptide Hydrolases; D002118:Calcium