The inhibitory GTP-binding protein (Gi) occurs in rat Leydig cells and is differentially modified by lutropin and 12-O-tetradecanoylphorbol 13-acetate.
Luteinizing-hormone (LH)-stimulated cyclic AMP production in rat testis Leydig cells was desensitized by both LH and 12-O-tetradecanoylphorbol 13-acetate (TPA). However, TPA, but not LH, enhanced the subsequent response to cholera toxin. Treatment of the cells with pertussis toxin potentiated cyclic AMP production in both control and LH-desensitized cells, but did not potentiate further the responses obtained by TPA pretreatment. The results implicate the presence of an inhibitory GTP-binding protein (Gi), which may be inhibited by TPA. The presence of a Gi-like protein within the plasma membrane of Leydig cells was demonstrated by pertussis-toxin-catalysed [32P]ADP-ribosylation of a Mr-40000-41000 protein.
D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D066298:In Vitro Techniques; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D037342:Pertussis Toxin; D051381:Rats; D011919:Rats, Inbred Strains; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D008565:Membrane Proteins; D010566:Virulence Factors, Bordetella; D000244:Adenosine Diphosphate; D007986:Luteinizing Hormone; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate