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Labeling of specific proteins in rat ovarian plasma membranes with [γ‐ 32 P]GTP
Author(s) -
Amir-Zaltsman Yehudith,
Ezra Elhanan,
Walker Naomi,
Lindner Hans R.,
Salomon Yoram
Publication year - 1980
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(80)80429-7
Subject(s) - library science , chemistry , computer science
Guanosine 5’triphosphate (GTP) has been implicated in a number of biological processes associated with protein synthesis [ 11, microtubular function [2,3] and in the control exerted by a large number of hormones [4]. Our interest in plasma membrane-associated reactions that specifically utilize GTP has been stimulated by the recognition that this nucleotide is directly involved in the control of adenylate cyclase activity [4] and by the demonstration of specific binding sites for GTP in plasma membranes of hepatocytes and adipocytes [.5]. A hormone-sensitive GTPase in turkey erythrocytes [6] and a GTP-binding protein associated with pigeon erythrocyte adenylate cyclase have been described [7]. We undertook a search for GTP-dependent phosphorylation in ovarian membranes since in vitro desensitization of LH-sensitive adenylate cyclase has been postulated to involve phosphorylation reactions [8,9]. This desensitization process in the rat ovary is dependent on low concentrations of GTP even in the presence of ATP [ 10-121. Similar findings have been made also in normal rat kidney cells [ 131. Here we report evidence that [T-“~P] GTP preferentially labels two proteins in rat ovary and parotid membranes [ 141 that differ structurally from the proteins that are substrates for ADP-ribosylation by cholera toxin [15-l 71 and which are thought to be involved in the regulation of adenylate cyclase by GTP.