Subcellular localization of a low Mr GTP-binding protein, c25KG, in resting and stimulated human platelets.
Subcellular fractions were prepared from human platelets by sucrose density gradient centrifugation and the presence of a GTP-binding protein, c25KG, was analyzed by immunoblotting. c25KG was found to be located in plasma membrane and alpha-granule fractions in resting platelets by immunoblot analysis. Disappearance of the protein by the pronase treatment of intact alpha-granules indicated that c25KG is exposed on the cytoplasmic face of the granules. Activation of platelets by thrombin induced the redistribution of c25KG from alpha-granules to plasma membranes. On the other hand, Gi2, which is the main pertussis toxin-substrate in human platelets, was predominantly present in plasma membranes and thrombin-stimulation did not alter its distribution.
Department of Biochemistry, Gifu University School of Medicine, Japan.
K
K
Nagata
Y
Y
Nozawa
D001792:Blood Platelets / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology; D002458:Cell Fractionation; D003594:Cytoplasmic Granules / Q000737:chemistry / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D019204:GTP-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008970:Molecular Weight; D013347:Subcellular Fractions / Q000378:metabolism; D013917:Thrombin / Q000494:pharmacology*
D013917:Thrombin; D019204:GTP-Binding Proteins; D002118:Calcium