Presence of a novel form of phosphatidylinositol 4-kinase in rat liver.
Rat liver microsomes contain two distinct forms of PtdIns 4-kinase which were resolved by heparin-Sepharose chromatography. One enzyme was identified as the type II PtdIns kinase previously isolated from exocytotic vesicles. The other enzyme, however, was a novel PtdIns 4-kinase isoform with properties differing from any other PtdIns kinase so far characterized. Both kinases were recognized by a monoclonal antibody specific for type II PtdIns 4-kinase, but the novel enzyme was considerably less sensitive to inhibition by adenosine and Ca2+ than type II enzymes, and in addition was specifically inhibited by submillimolar concentrations of dithioerythritol. The presence of a novel PtdIns 4-kinase isoform in rat liver raises the question of whether this enzyme is unique for this organ or whether it has a more widespread distribution but so far has avoided detection.
Olsson
H
H
Chemical Centre, University of Lund, Sweden.
Martínez-Arias
W
W
Drøbak
B K
BK
Jergil
B
B
D019870:1-Phosphatidylinositol 4-Kinase; D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent / Q000494:pharmacology; D002846:Chromatography, Affinity; D004226:Dithioerythritol / Q000494:pharmacology; D007527:Isoenzymes / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008862:Microsomes, Liver / Q000201:enzymology*; D010718:Phosphatidylserines / Q000494:pharmacology; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000302:isolation & purification* / Q000378:metabolism; D051381:Rats
D000911:Antibodies, Monoclonal; D002413:Cations, Divalent; D007527:Isoenzymes; D010718:Phosphatidylserines; D004226:Dithioerythritol; D017853:Phosphotransferases (Alcohol Group Acceptor); D019870:1-Phosphatidylinositol 4-Kinase; D000241:Adenosine; D002118:Calcium