Aminoacylase I is not a glycolipid-anchored ectoenzyme in pig kidney.
Subcellular fractionation of pig kidney cortex revealed that aminoacylase I (EC 3.5.1.14, N-acyl-L-amino-acid aminohydrolase) is predominantly a soluble enzyme with only 0.5% of the total activity being recovered in the membrane fraction. The aminoacylase I activity associated with the membrane preparations displayed neither rapid release following incubation with phosphatidylinositol-specific phospholipase C from Bacillus thuringiensis nor the distinctive differential pattern of detergent solubilization which was seen with glycosyl-phosphatidylinositol-anchored proteins (renal dipeptidase, alkaline phosphatase). When fractionated by phase separation in Triton X-114, integral membrane proteins of kidney microvillar membranes partitioned predominantly (greater than 90%) into the detergent-rich phase. In contrast, only 3.7% of aminoacylase I activity associated with microvillar membranes partitioned into the detergent-rich phase. Aminoacylase I activity of pig kidney would therefore appear to be a hydrophilic protein in nature and is not, as suggested previously, a G-PI-anchored integral membrane protein.
Greenhough
K J
KJ
Department of Biochemistry and Molecular Biology, University of Leeds, U.K.
Turner
A J
AJ
D000581:Amidohydrolases / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D006017:Glycolipids / Q000032:analysis*; D017261:Glycosylphosphatidylinositols; D007672:Kidney Cortex / Q000201:enzymology*; D007700:Kinetics; D008871:Microvilli / Q000201:enzymology; D010716:Phosphatidylinositols / Q000032:analysis*; D013347:Subcellular Fractions / Q000201:enzymology; D013552:Swine
D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D010716:Phosphatidylinositols; D000581:Amidohydrolases; C019672:aminoacylase I