The inhibitory guanine nucleotide-binding regulatory subunit of adenylate cyclase has an adenylate cyclase-independent modulatory effect on ACTH secretion from mouse pituitary tumor cells

1985 ◽  
Vol 126 (2) ◽  
pp. 941-947 ◽  
Author(s):  
Seymour Heisler
Keyword(s):  
Adenylate Cyclase ◽  
Tumor Cells ◽  
Pituitary Tumor ◽  
Nucleotide Binding ◽  
Regulatory Subunit ◽  
Guanine Nucleotide ◽  
Acth Secretion ◽  
Guanine Nucleotide Binding ◽  
Mouse Pituitary

Forskolin stimulation of adenylate cyclase in human thyroid membranes

1985 ◽  
Vol 108 (2) ◽  
pp. 200-205 ◽  
Author(s):  
Kikuo Kasai ◽  
Yoshinobu Suzuki ◽  
Masaki Hiraiwa ◽  
Hisamoto Kuroda ◽  
Tatsushi Emoto ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Nucleotide Binding ◽  
Guanine Nucleotides ◽  
Human Thyroid ◽  
Guanine Nucleotide ◽  
Guanine Nucleotide Binding ◽  
Stimulation Of

Abstract. Forskolin stimulates adenylate cyclase in human thyroid membranes approximately 7-fold with halfmaximal stimulation occurring at 5–10 μm. Guanine nucleotides are not required for stimulation of the enzyme by forskolin. Forskolin-stimulation is additive or greater than additive with that of TSH or Gpp(NH)p-(above 1 μm). Different from TSH- or Gpp(NH)p-stimulation of adenylate cyclase, uncoupling of the guanine nucleotide-binding regulatory component by increasing concentrations of MnCl2 did not result in uncoupling of forskolin stimulation. The finding indicates that forskolin may mainly act on the catalytic component of adenylate cyclase. From the present study, it is suggested that the diterpene forskolin stimulates adenylate cyclase in human thyroid membranes by a novel mechanism that differs from TSH- or Gpp(NH)p-stimulation, and that the diterpene may be a useful tool to investigate the metabolism of thyroid and its regulation in normal and pathological situations.

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