151. Specific binding sites for inositol 1,3,4,5-tetrakisphosphate are located predominantly in the plasma membranes of human platelets
- Author
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Vijay V. Kakkar, Yatin Patel, Peter J. Cullen, K S Authi, and R F Irvine
- Subjects
Blood Platelets ,Inositol Phosphates ,Receptors, Cytoplasmic and Nuclear ,Biology ,Biochemistry ,Binding, Competitive ,chemistry.chemical_compound ,Animals ,Humans ,Platelet ,Inositol ,Binding site ,Receptor ,Inositol phosphate ,Molecular Biology ,chemistry.chemical_classification ,Binding Sites ,Cell Membrane ,Cell Biology ,Electrophoresis ,Membrane ,chemistry ,Cattle ,Phosphorus Radioisotopes ,Intracellular ,Research Article - Abstract
In the present study we describe the characterization and localization of Ins(1,3,4,5)P4-binding sites in human platelet membranes. Specific binding sites for Ins(1,3,4,5)P4 have been identified on mixed, plasma and intracellular membranes from neuraminidase-treated platelets using highly purified carrier-free [32P]Ins(1,3,4,5)P4. The displacement of Ins(1,3,4,5)P4 from these sites by Ins(1,4,5)P3 and InsP6 occurs at greater than two orders of magnitude higher concentrations and with Ins(1,3,4,5,6)P5 at about 40-fold higher concentrations than with Ins(1,3,4,5)P4. The membranes were further separated by free-flow electrophoresis into plasma and intracellular membranes. The Ins(1,3,4,5)P4-binding sites separated with plasma membranes, and showed similar affinities and specificities as mixed membranes, whereas Ins(1,4,5)P3-binding sites were predominantly in the intracellular membranes. These results suggest a predominantly plasma membrane location for putative Ins(1,3,4,5)P4 receptors in human platelets.
- Published
- 1994