Rab3B in human platelet is membrane bound and interacts with Ca(2+)/calmodulin.
The subcellular distribution of Rab3B in fresh and aged platelets was determined and majority of the protein was localized with the particulate fraction with only a minor amount detected in the cytosol. Rab3B was pulled out from platelet particulate fraction with GST-RabGDI-alpha fusion protein. Using GST-Rab3B in in vitro pull-down ... experiments, the binding of calmodulin from platelet cytosol to Rab3B was demonstrated. In the reverse experiment, binding of Rab3B from platelet particulate and cytosolic fractions to Sepharose-CaM beads was also observed. The interaction between Rab3B and calmodulin was Ca(2+)-dependent but independent of the guanine nucleotide status of Rab3B. These findings provide evidence that Rab3B is primarily localized with the particulate fraction and that Ca(2+)/calmodulin could regulate function of this GTPase in the platelet.
Mesh Terms:
Blood Platelets, Calcium, Calmodulin, Cytosol, Guanine Nucleotide Dissociation Inhibitors, Guanosine 5'-O-(3-Thiotriphosphate), Guanosine Diphosphate, Humans, Membranes, Protein Binding, Recombinant Fusion Proteins, Subcellular Fractions, rab3 GTP-Binding Proteins
Blood Platelets, Calcium, Calmodulin, Cytosol, Guanine Nucleotide Dissociation Inhibitors, Guanosine 5'-O-(3-Thiotriphosphate), Guanosine Diphosphate, Humans, Membranes, Protein Binding, Recombinant Fusion Proteins, Subcellular Fractions, rab3 GTP-Binding Proteins
Biochem. Biophys. Res. Commun.
Date: Dec. 21, 2001
PubMed ID: 11741295
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