Subcellular fractionation of pig kidney cortex revealed that aminoacylase I (EC 188.8.131.52, 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 thuringuensis 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 (> 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.
|Number of pages||5|
|Journal||Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular|
|Publication status||Published - 15 Feb 1991|