The reported cDNA sequence for phospholipase C alpha encodes protein disulfide isomerase, isozyme Q-2 and not phospholipase-C.
We have previously shown that the cDNA sequence published for the rat gene encoding phosphatidylinositol specific phospholipase C alpha (1) may be identical to the sequence of a new isoform of protein disulfide isomerase, Isozyme Q2 (2). To determine whether the presumed phospholipase C alpha gene encodes phospholipase C or protein disulfide isomerase, we have now expressed the cDNA in Escherichia coli and find that the 55.5 kDa protein that it synthesized contains no phospholipase C activity. Moreover, an extract of Escherichia coli containing the expressed protein shows a concentration dependent increase in protein disulfide isomerase activity. The expressed protein is identical to protein disulfide isomerase, Isozyme Q2 on SDS-PAGE and by Western blot analysis. These current studies confirm that the published sequence of phospholipase C alpha is, in fact, the sequence of protein disulfide isomerase, Isozyme Q2.
Department of Pharmacology, University of Minnesota, Minneapolis 55455.
S P
SP
Srivastava
J A
JA
Fuchs
J L
JL
Holtzman
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D005822:Genetic Vectors; D007527:Isoenzymes / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D007535:Isomerases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D054801:Phosphoinositide Phospholipase C; D010727:Phosphoric Diester Hydrolases / Q000235:genetics*; D019704:Protein Disulfide-Isomerases; D051381:Rats; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D015183:Restriction Mapping; D010738:Type C Phospholipases / Q000235:genetics*
D007527:Isoenzymes; D011994:Recombinant Proteins; D004247:DNA; D010727:Phosphoric Diester Hydrolases; D010738:Type C Phospholipases; D054801:Phosphoinositide Phospholipase C; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D007535:Isomerases; D019704:Protein Disulfide-Isomerases