Detection of 23-27 kDa GTP-binding proteins in platelets and other cells.
Membrane proteins from rabbit and human platelets were separated by SDS/polyacrylamide-gel electrophoresis and the resolved polypeptides blotted on nitrocellulose. A family of GTP-binding proteins, termed Gn proteins, was detected by incubation of these blots with [alpha-32P]GTP in the presence of Mg2+. A major Gn protein with a molecular mass of 27 kDa (Gn27) and lesser amounts of 23, 24 and 25 kDa Gn proteins were observed in platelet membranes; much smaller amounts were in the platelet soluble fraction. Binding of [alpha-32P]GTP by platelet Gn proteins was blocked by GDP, GTP or guanosine 5'-[gamma-thio]triphosphate, but not by GMP or adenosine 5'-[beta gamma-imido]triphosphate. Rabbit and human red-cell membranes contained only Gn27. When rat tissues were analysed for Gn proteins, the largest amounts were found in brain, which contained two membrane-bound forms (Gn27 and Gn26) and a soluble form (Gn26).
D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004910:Erythrocyte Membrane / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000097:blood*; D006160:Guanosine Triphosphate / Q000097:blood; D006801:Humans; D011817:Rabbits; D051381:Rats; D013347:Subcellular Fractions / Q000378:metabolism; D014018:Tissue Distribution
D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins