Membrane bound guanylate cyclase in rat fat cell plasma membranes: influence of divalent cations on calcium activation.
Rat fat cell plasma membrane preparations were used to study the effect of Mn2+, Mg2+, Ca2+ on guanylate cyclase activity. Among these three cations, Mn2+ was the most effective in activating the enzyme; Mg2+ and Ca2+ were 23% and 10% respectively as effective as Mn2+ in activating the enzyme. Low concentrations of Ca2+ (1 microM) increased the rate of cGMP formation at MgGTP concentrations ranging from 0.3 to 2 mM. This effect was less at higher concentrations of Ca2+ and was independent of the presence of excess Mg2+. Ca2+ (100 microM) had only a marginal stimulatory effect on the MnGTP-dependent enzyme.
D000273:Adipose Tissue / Q000201:enzymology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002462:Cell Membrane / Q000201:enzymology; D004789:Enzyme Activation; D006162:Guanylate Cyclase / Q000032:analysis*; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008345:Manganese / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D008345:Manganese; D006162:Guanylate Cyclase; D008274:Magnesium; D002118:Calcium