title: Presence of guanine nucleotide-binding proteins in a plant hypocotyl microsomal fraction.
abstract: The presence of specific guanine nucleotide-binding proteins in a zucchini (Cucurbita pepo L.) hypocotyl microsomal fraction was investigated. Polypeptides were separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis and transferred to nitrocellulose. Incubation of nitrocellulose blots with [alpha-32P]GTP and [gamma-32P]GTP indicated the presence of four specific and distinct GTP-binding proteins with molecular masses of approx. 23.4 kDa, 24.8 kDa, 26.6 kDa and 28.5 kDa. Binding of [alpha-32P]GTP could be completely prevented by 30 microM GDP or 10 microM guanosine 5'[gamma-thio]triphosphate. This report presents evidence for the presence in a microsomal fraction from zucchini hypocotyls of Gn-proteins as defined by Bhullar and Haslam (1987) Biochem.J. 245, 617-620. The four plant proteins resemble animal Gn-proteins when molecular weights and GTP-binding specificities are considered.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001345:Autoradiography; D004591:Electrophoresis, Polyacrylamide Gel; D019204:GTP-Binding Proteins / Q000032:analysis*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006153:Guanosine Diphosphate / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D008861:Microsomes / Q000032:analysis; D008862:Microsomes, Liver / Q000032:analysis; D008970:Molecular Weight; D010944:Plants / Q000032:analysis*; D051381:Rats; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D013873:Thionucleotides; D006153:Guanosine Diphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D019204:GTP-Binding Proteins; D008274:Magnesium