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The formation of lysophosphatidylinositol phosphate in human platelet microsomes
Author(s) -
Thomas L. M.,
Holub B. J.
Publication year - 1987
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02537292
Subject(s) - phosphatidylinositol , microsome , chemistry , pi , phosphorylation , kinase , phosphate , intracellular , biochemistry , enzyme , second messenger system , incubation , clinical chemistry , inositol , stimulation , inositol phosphate , chromatography , biology , endocrinology , receptor
The formation of lysophosphatidylinositol phosphate (lysoPIP) from lysophosphatidylinositol (lysoPI) via kinase activity was studied in microsomal preparations from human platelets. For this purpose, [ 3 H]lysoPI or [ 3 H]phosphatidylinositol ([ 3 H]PI) was prepared and incubated in the presence or absence of ATP, MgCl 2 and Triton X‐100, and the appearances of radioactivity in [ 3 H]lysoPIP and [ 3 H]phosphatidylinositol phosphate ([ 3 H]PIP), respectively, were monitored using thin layer chromatography. Both lysoPI and PI phosphorylations were completely dependent upon the presence of ATP and MgCl 2 in the incubation medium; Triton X‐100 addition stimulated both reactions, with the stimulation of PI conversion being considerably greater than that for lysoPI conversion. The present results demonstrate that lysoPI can be converted to lysoPIP by phosphorylation in human platelet microsomes. The potential significance of this enzymatic reaction in stimulated cells is discussed in relation to the generation of inositol‐1,4,5‐trisphosphate, an important intracellular second messenger.