Abstract
Summary Ca 2+ at a concentration as low as 3 μM stimulated guanylate cyclase activity in membranes of cultured Balb 3T3 fibroblasts when Mg 2+ was the major bivalent cation. If the enzyme was assayed with Mn 2+ as the major cation, Ca 2+ caused either inhibition or stimulation depending on conditions but these effects of Ca 2+ occurred at much higher concentrations. The addition of NaCl decreased the activity with Mg 2+ but increased the degree of stimulation of Ca 2+ . We suggest that the activity of guanylate cyclase in vitro with Mg 2+ represents its behavior in vivo and that Ca 2+ regulates cyclic GMP in cells by directly stimulating guanylate cyclase activity.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
