Molecular details of cAMP generation in mammalian cells: a tale of two systems.
The second messenger cAMP has been extensively studied for half a century, but the plethora of regulatory mechanisms controlling cAMP synthesis in mammalian cells is just beginning to be revealed. In mammalian cells, cAMP is produced by two evolutionary related families of adenylyl cyclases, soluble adenylyl cyclases (sAC) and transmembrane adenylyl cyclases (tmAC). These two enzyme families serve distinct physiological functions. They share a conserved overall architecture in their catalytic domains and a common catalytic mechanism, but they differ in their sub-cellular localizations and responses to various regulators. The major regulators of tmACs are heterotrimeric G proteins, which transduce extracellular signals via G protein-coupled receptors. sAC enzymes, in contrast, are regulated by the intracellular signaling molecules bicarbonate and calcium. Here, we discuss and compare the biochemical, structural and regulatory characteristics of the two mammalian AC families. This comparison reveals the mechanisms underlying their different properties but also illustrates many unifying themes for these evolutionary related signaling enzymes.
Kamenetsky
Margarita
M
Department of Pharmacology, Joan and Sanford I. Weill Medical College of Cornell University, New York, NY 10021, USA.
Middelhaufe
Sabine
S
Bank
Erin M
EM
Levin
Lonny R
LR
Buck
Jochen
J
Steegborn
Clemens
C
D000262:Adenylyl Cyclases / Q000737:chemistry / Q000145:classification / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D000242:Cyclic AMP / Q000096:biosynthesis*; D019143:Evolution, Molecular; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000145:classification / Q000378:metabolism; D008969:Molecular Sequence Data
D007527:Isoenzymes; D000242:Cyclic AMP; D000262:Adenylyl Cyclases