title: Proteolytic release of human angiotensin-converting enzyme expressed in Chinese hamster ovary cells is enhanced by phorbol ester.
abstract: Membrane-bound angiotensin-converting enzyme (ACE) expressed in Chinese hamster ovary (CHO) cells is proteolytically released in soluble form into the medium. We find that this release is stimulated up to 50-fold by phorbol-12,13-dibutyrate and also by the addition of fresh, serum-containing media. Concomitant with the enhanced release is a marked decrease in levels of membrane-bound ACE, down to 7% of resting levels in the case of phorbol ester stimulation. Staurosporine, a protein kinase C (PKC) inhibitor, abolishes the phorbol ester effect. Kinetic analysis of the stimulated release rate indicates that it is first order, likely due to substrate depletion; calculated half times, t1/2, are 174 +/- 12 min and 40 +/- 6 min for the media-change and phorbol ester stimulated rates, respectively. Thus, release of membrane-bound ACE in CHO cells is regulated, in part, by a PKC-dependent mechanism.
authors: Department of Medical Biochemistry, University of Cape Town Medical School, Observatory, South Africa.
authors: M R
authors: MR
authors: Ehlers
authors: R R
authors: RR
authors: Scholle
authors: J F
authors: JF
authors: Riordan
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000201:enzymology; D006224:Cricetinae; D010450:Endopeptidases / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D007703:Peptidyl-Dipeptidase A / Q000096:biosynthesis / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D019311:Staurosporine; D014162:Transfection
chemical_list: D000470:Alkaloids; D011480:Protease Inhibitors; D011994:Recombinant Proteins; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C; D010450:Endopeptidases; D007703:Peptidyl-Dipeptidase A; D019311:Staurosporine