Gonadotrophin-releasing hormone receptor agonist-mediated down-regulation of Gq alpha/G11 alpha (pertussis toxin-insensitive) G proteins in alpha T3-1 gonadotroph cells reflects increased G protein turnover but not alterations in mRNA levels.
Prolonged exposure of alpha T3-1 pituitary gonadotrophs to a gonadotrophin-releasing hormone receptor agonist results in marked down-regulation of the pertussis toxin-insensitive G proteins Gq alpha and G11 alpha. The turnover of Gq alpha/G11 alpha was substantially accelerated in the presence of agonist. By contrast, the rate of degradation of the G protein Gi2 alpha was unaffected by agonist treatment. Analysis of Gq alpha/G11 alpha mRNA levels by reverse transcription-PCR demonstrated no detectable differences between control and agonist-treated cells. These studies indicate that gonadotrophin-releasing hormone receptor agonist-mediated down-regulation of Gq alpha/G11 alpha is a reflection of enhanced proteolysis of the activated G proteins.
Shah
B H
BH
Division of Biochemistry and Molecular Biology, University of Glasgow, Scotland, United Kingdom.
MacEwan
D J
DJ
Milligan
G
G
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers; D019204:GTP-Binding Proteins / Q000096:biosynthesis* / Q000302:isolation & purification; D005786:Gene Expression Regulation / Q000187:drug effects*; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D037342:Pertussis Toxin; D010902:Pituitary Gland; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis; D011974:Receptors, LH / Q000819:agonists*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D017931:DNA Primers; C082465:LHRH ethylamide, des-Gly(10)-Ala(6)-; D012333:RNA, Messenger; D011974:Receptors, LH; D010566:Virulence Factors, Bordetella; D007987:Gonadotropin-Releasing Hormone; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins