Unknown

Dataset Information

0

Hydrolysis of membrane phospholipids by phospholipases of rat liver lysosomes.


ABSTRACT: (1) The hydrolysis of (32)P- or myo-[2-(3)H]inositol-labelled rat liver microsomal phospholipids by rat liver lysosomal enzymes has been studied. (2) The relative rates of hydrolysis of phospholipids at pH4.5 are: sphingomyelin>phosphatidylethanolamine>phosphatidylcholine> phosphatidylinositol. (3) The predominant products of phosphatidylcholine and phosphatidylethanolamine hydrolysis are their corresponding lyso-compounds, indicating a slow rate of total deacylation. (4) Ca(2+) inhibits the hydrolysis of all phospholipids, though only appreciably at high (>5mm) concentration. The hydrolysis of sphingomyelin is considerably less sensitive to Ca(2+) than that of glycerophospholipids. (5) Analysis of the water-soluble products of phosphatidylinositol hydrolysis (by using myo-[(3)H]inositol-labelled microsomal fraction as a substrate) produced evidence that more than 95% of the product is phosphoinositol, which was derived by direct cleavage from phosphatidylinositol, rather than by hydrolysis of glycerophosphoinositol. (6) This production of phosphoinositol, allied with negligible lysophosphatidylinositol formation and a detectable accumulation of diacylglycerol, indicates that lysosomes hydrolyse membrane phosphatidylinositol almost exclusively in a phospholipase C-like manner. (7) Comparisons are drawn between the hydrolysis by lysosomal enzymes of membrane substrates and that of pure phospholipid substrates, and also the possible role of phosphatidylinositol-specific lysosomal phospholipase C in cellular phosphatidylinositol catabolism is discussed.

SUBMITTER: Richards DE 

PROVIDER: S-EPMC1161342 | biostudies-other | 1979 Aug

REPOSITORIES: biostudies-other

Similar Datasets

| S-EPMC1158381 | biostudies-other
| S-EPMC1146898 | biostudies-other
| S-EPMC1149702 | biostudies-other
| S-EPMC4884535 | biostudies-literature
2018-11-02 | GSE115489 | GEO
| S-EPMC1164280 | biostudies-other
| S-EPMC1186206 | biostudies-other
| S-EPMC1782372 | biostudies-literature
| S-EPMC1165823 | biostudies-other
| S-EPMC1264917 | biostudies-other