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Phospholipase C in rat liver plasma membranes
Author(s) -
Melin Per-Martin,
Sundler Roger,
Jergil Bengt
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)81189-9
Subject(s) - phosphatidylinositol , phospholipase c , phosphatidylinositol 4,5 bisphosphate , enzyme , phospholipase , biochemistry , chemistry , gtp' , membrane , phospholipid , phosphoinositide phospholipase c , signal transduction
Phospholipase C activity against phosphoinositides in isolated rat liver plasma membranes has been examined using exogenous substrates. The enzyme hydrolyzed phosphatidylinositol 4,5‐bisphosphate 30–40‐times faster than phosphatidylinositol 4‐monophosphate, while phosphatidylinositol was not a substrate. Maximum activity was observed with 1.1 mM phosphatidylinositol 4,5‐bisphosphate at pH 5.0. The enzyme was stimulated by micromolar concentrations of Ca 2+ . The GTP analogue guanylyl (β,γ‐methylene)diphosphonate enhanced phospholipase C activity at and above 0.3 μM Ca 2+ , but was inhibitory at 0.1 μM Ca 2+ . This supports the suggestion that plasma membrane phospholipase C is regulated by guanine nucleotide‐binding protein, but indicates a regulatory mechanism different from that of other enzymes regulated by such proteins.