Sensitivity of the human myometrial adenylate cyclase to calcium and calmodulin.
The calcium-calmodulin-dependent regulation of adenylate cyclase was studied in membranes from pregnant human myometrium. In the absence or presence of exogenous calmodulin, free calcium concentrations greater than 50 nmol/l inhibited the adenylate cyclase activity. Activation of the enzyme by calmodulin (0.1-1 mumol/l) was calcium-dependent and maximal at 10 nmol/l free calcium. The myometrial adenylate cyclase activity was stimulated by the guanyl nucleotide, Gpp(NH)p. In the presence of the guanyl nucleotide, the activatory effect of the calcium-calmodulin complex disappeared. The activatory effect of exogenous calmodulin was dependent on endogenous calmodulin present in the myometrial membranes. Trifluoroperazine and calmidazolium were able to inhibit the adenylate cyclase activity.
Doualla-Bell Kotto Maka
F
F
INSERM U. 166, Groupe de Recherches sur l'Endocrinologie de la Reproduction, Paris, France.
Breuiller
M
M
Leroy
M J
MJ
Josserand
S
S
Ferre
F
F
D000262:Adenylyl Cyclases / Q000502:physiology*; D002118:Calcium / Q000502:physiology*; D002147:Calmodulin / Q000502:physiology*; D005260:Female; D006801:Humans; D009215:Myometrium / Q000201:enzymology*; D011247:Pregnancy / Q000378:metabolism*
D002147:Calmodulin; D000262:Adenylyl Cyclases; D002118:Calcium