Cytidylate cyclase activity is stimulated via activation of a guanine nucleotide-binding protein.
Cytidylate cyclase is a membrane-bound enzyme which catalyzes the biosynthesis of cytidine 3',5'-cyclic monophosphate (cCMP) from CTP. By using a sensitive and specific enzyme immunoassay method, we evaluated the participation of guanine nucleotide-binding protein (G-protein) in the regulation of cytidylate cyclase activity in rat brain and other tissues. AlF4-, an activator of G-proteins, effectively elevated the cyclase activity. The stimulation by GTP gamma S, a nonhydrolyzable GTP analogue, was also observed in time- and concentration-dependent manner during the preincubation and this effect was competitively inhibited by the addition of GDP beta S. However, islet-activating protein and cholera toxin which affected adenylate cyclase activity had no effect on cytidylate cyclase activity. These results indicate that cytidylate cyclase is associated with a certain G-protein and its activity is regulated by the mode different from that of adenylate cyclase.
Muto
N
N
Department of Immunochemistry, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
Kanoh
M
M
Yamamoto
I
I
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology; D019204:GTP-Binding Proteins / Q000502:physiology*; D066298:In Vitro Techniques; D008190:Lyases / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D019761:Phosphorus-Oxygen Lyases; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D019204:GTP-Binding Proteins; D008190:Lyases; D019761:Phosphorus-Oxygen Lyases; C019978:cytidylate cyclase; D000262:Adenylyl Cyclases