title: Ectoenzymes of the kidney microvillar membrane. Aminopeptidase P is anchored by a glycosyl-phosphatidylinositol moiety.
abstract: The mode of membrane anchorage of three kidney microvillar membrane ectoenzymes has been examined. The release of aminopeptidase P (EC 3.4.11.9) from kidney membranes by bacterial phosphatidylinositol-specific phospholipase C (PI-PLC) and the pattern of detergent solubilization of this ectoenzyme implies that it is anchored to the membrane via a covalently attached glycosyl-phosphatidylinositol moiety. As deduced by phase separation in Triton X-114, octyl-glucoside solubilized the amphipathic form of aminopeptidase P, whereas the PI-PLC-released form displayed hydrophilic properties. In contrast, the pattern of detergent solubilization of two microvillar carboxypeptidases and their resistance to release from the membrane by bacterial PI-PLC suggest that these two ectoenzymes are not anchored via phosphatidylinositol.
authors.affiliation: Department of Biochemistry, University of Leeds, England.
authors.forename: N M
authors.initials: NM
authors.lastname: Hooper
authors.forename: A J
authors.initials: AJ
authors.lastname: Turner
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000626:Aminopeptidases / Q000378:metabolism*; D002268:Carboxypeptidases / Q000378:metabolism; D002458:Cell Fractionation / Q000379:methods; D006801:Humans; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D008871:Microvilli / Q000201:enzymology* / Q000648:ultrastructure; D010447:Peptide Hydrolases / Q000378:metabolism
chemical_list: D000469:Alkaline Phosphatase; C025427:carboxypeptidase P; D002268:Carboxypeptidases; D010447:Peptide Hydrolases; D000626:Aminopeptidases; C022750:X-Pro aminopeptidase