Involvement of the regulatory protein (Ns) in the maturation of ACTH-sensitive adenylate cyclase of ovine fetal adrenal during late gestation.
The responsiveness to several stimuli of the adenylate cyclase of crude adrenal membranes from fetal and neonate lambs has been measured under different conditions. The response to Gpp(NH)p, ACTH1-24 + Gpp(NH)p and NaF was significantly lower in membranes from fetuses than from neonate lambs, whereas the response to forskolin was similar. Addition of human erythrocyte ghosts to fetal adrenal membranes enhanced the stimulation of cyclase by NaF and Gpp(NH)p, which became similar to that observed in membranes from neonates. However, such a "complementation' did not enhance the response of the enzyme to ACTH1-24. The adenylate cyclase activity displayed a biphasic response to GTP under basal conditions or when stimulated by forskolin. The magnitude of the inhibition achieved with 10(-3) M GTP was similar in fetal and neonatal adrenal membranes. These data, together with previous results (Endocrinology, 1981, 108, 2114-2119), show that the maturation of the ACTH-sensitive adenylate cyclase system of the ovine fetal adrenal gland involves an enhancement of the number of ACTH receptors and a development of the Ns subunit, whereas the catalytic site is hardly (if at all) involved in this process.
Durand
P
P
Cathiard
A M
AM
Saez
J M
JM
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000311:Adrenal Glands / Q000196:embryology / Q000201:enzymology*; D000324:Adrenocorticotropic Hormone / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D005576:Colforsin; D003366:Cosyntropin / Q000494:pharmacology; D004224:Diterpenes / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000201:enzymology; D005260:Female; D019204:GTP-Binding Proteins / Q000502:physiology*; D005865:Gestational Age; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D006801:Humans; D011247:Pregnancy; D012756:Sheep; D012969:Sodium Fluoride / Q000494:pharmacology
D004224:Diterpenes; D003366:Cosyntropin; D005576:Colforsin; D006165:Guanylyl Imidodiphosphate; D012969:Sodium Fluoride; D000324:Adrenocorticotropic Hormone; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases