Liver microsomes contain multiple forms of inositol 1,4,5-trisphosphate binding proteins: identification by nitrocellulose blot overlay.
A group of proteins binding to inositol 1,4,5-trisphosphate (IP3) has been identified in rat liver microsomes by a nitrocellulose blot-overlay technique. Proteins were resolved by SDS-PAGE, blotted on nitrocellulose and incubated with [32P]IP3 followed by autoradiography. Approximately eight IP3-binding polypeptides ranging M(r) 23-50 kDA were present exclusively in microsomes; these were absent from plasma membrane and mitochondrial fractions. Binding of [32P]IP3 to these proteins was displaceable to a great extent by 5 microM unlabeled IP3 but not by 10 microM IP1, IP2, IP4, ATP, or GTP gamma S. These results suggest that liver microsomes contain multiple forms of IP3-binding proteins that can be detected by this new method.
Ali
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Department of Internal Medicine, Creighton University School of Medicine, Omaha 68178.
Agrawal
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DK
D000818:Animals; D002623:Chemistry Techniques, Analytical / Q000379:methods; D003101:Collodion; D004591:Electrophoresis, Polyacrylamide Gel; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000737:chemistry*; D011485:Protein Binding; D011506:Proteins / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions
D011506:Proteins; D015544:Inositol 1,4,5-Trisphosphate; D003101:Collodion