Structure, Mechanism, and Regulation of Mammalian Adenylyl Cyclase

stimulatory G-protein α subunit inhibitory G-protein α subunit G-protein βγ subunit Ca2+/calmodulin-dependent protein kinase The discovery of 3′,5′-cyclic adenosine monophosphate (cAMP) in the late 1950s by Sutherland and co-workers was the pivotal event that led to our current paradigm of hormone signaling through second messengers. Despite the subsequent discovery of many other second messengers, cAMP has never left center stage. The adenylyl cyclases are the family of enzymes that synthesize cAMP (1Sunahara R.K. Dessauer C.W. Gilman A.G. Annu. Rev. Pharmacol. Toxicol. 1996; 36: 461-480Crossref PubMed Scopus (732) Google Scholar, 2Xia Z.G. Storm D.R. Curr. Opin. Neurobiol. 1997; 7: 391-396Crossref PubMed Scopus (122) Google Scholar, 3Hanoune J. Pouille Y. Tzavara E. Shen T.S. Lipskaya L. Miyamoto N. Suzuki Y. Defer N. Mol. Cell. Endocrinol. 1997; 128: 179-194Crossref PubMed Scopus (139) Google Scholar, 4Cooper D.M.F. Adv. Second Messenger Phosphoprotein Res. 1998; : 32Google Scholar, 5Tang W.-J. Hurley J.H. Mol. Pharmacol. 1998; 54: 231-240Crossref PubMed Scopus (160) Google Scholar).Breakthroughs in determining the first structures of the mammalian adenylyl cyclase catalytic core (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google Scholar, 7Tesmer J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar) provide a new context for understanding the action of many regulators, both physiological and pharmacological: free metal ions, P-site inhibitors, forskolin, G-proteins, Ca2+/calmodulin, and protein phosphorylation. Understanding the catalytic mechanism of an enzyme is a prerequisite to understanding its regulation. Here I will describe the essentials of catalysis and then consider how these elements are controlled by each of the major regulators.Structure of Adenylyl CyclaseThe nine cloned isoforms of mammalian adenylyl cyclase share a primary structure consisting of two transmembrane regions, M1 and M2, and two cytoplasmic regions, C1 and C2 (8Krupinski J. Coussen F. Bakalyar H. Tang W.-J. Feinstein P.G. Orth K. Slaughter C. Reed R.R. Gilman A.G. Science. 1989; 244: 1558-1564Crossref PubMed Scopus (505) Google Scholar) (Fig.1). The transmembrane regions each contain six predicted membrane-spanning helices. The function of M1 and M2, aside from membrane localization, is unknown despite their topological analogy to transporters. The C1 and C2 regions are subdivided into C1a and C1b; and C2a and C2b. The C1a and C2a are well conserved, homologous to each other, and contain all of the catalytic apparatus (9Tang W.-J. Gilman A.G. Science. 1995; 268: 1769-1772Crossref PubMed Scopus (165) Google Scholar). C1a and C2a domains heterodimerize with each other in solution (10Yan S.-Z. Hahn D. Huang Z.-H. Tang W.-J. J. 1996; PubMed Scopus Google Scholar, Gilman A.G. Dessauer C.W. 1996; PubMed Scopus Google Scholar). domains from isoforms The is and The is in isoforms and C2 and C2a are to structure of the adenylyl cyclase C2 a with two C2 in a (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google Scholar). the two in the center of the to in the The is that the the The is the is to the domains of the I and Nature. 1997; PubMed Scopus Google Scholar, J. Liu Y. Ruoho A.E. G. Hurley J.H. Nature. 1997; Scopus Google C1a and C2 in a that is in structure to the C2 with in J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar). The is of the The by C.W. Gilman A.G. J. 1997; PubMed Scopus Google is the The is the by by both C1a and the is the two of two catalytic domains in the is an prerequisite of catalytic The of mammalian adenylyl cyclases the of C1a and is the for many other cyclases Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, J.H. Curr. Opin. 1998; PubMed Scopus Google Scholar). membrane cyclases and many of mammalian adenylyl cyclases are The mammalian C2 has (9Tang W.-J. Gilman A.G. Science. 1995; 268: 1769-1772Crossref PubMed Scopus (165) Google Scholar, G. Liu Y. J. Tang W.-J. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, Tang W.-J. C. 1998; PubMed Scopus Google by many of of the of two catalytic to the and has by the structure of the P-site J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google and Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, W.-J. Gilman A.G. 1995; PubMed Scopus Google Scholar, S.-Z. Huang Z.-H. Tang W.-J. J. 1997; PubMed Scopus Google Scholar, Hurley J.H. Hurley 1998; PubMed Scopus Google Scholar, R.K. J.J.G. Sprang S.R. Gilman A.G. J. 1998; PubMed Scopus Google Scholar). the is is for and from C2 with the and of the of C1 a by the of these the of adenylyl into a cyclase R.K. J.J.G. Sprang S.R. Gilman A.G. J. 1998; PubMed Scopus Google Scholar). is of a that to the and cyclases into adenylyl cyclases by their and to their adenylyl cyclase and Hurley J.H. Hurley 1998; PubMed Scopus Google Scholar, R.K. J.J.G. Sprang S.R. Gilman A.G. J. 1998; PubMed Scopus Google is by that the and by with are by are by and The is of a the that is of an (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google of two Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, W.-J. Gilman A.G. 1995; PubMed Scopus Google Scholar). The P-site a with both of J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar). is for a mechanism J. J. 1995; PubMed Scopus Google Scholar, G. D. J. 1998; PubMed Scopus Google Scholar). free the other a with for the The the of a the of a the of a its to Nature. 1998; PubMed Scopus Google Scholar, C. Nature. 1998; PubMed Scopus Google Scholar, J. H. 1997; 36: PubMed Scopus Google Scholar, Nature. 1998; PubMed Scopus Google a for the of two in the adenylyl cyclase The metal to the in the adenylyl cyclase all in a Nature. 1998; PubMed Scopus Google Scholar, J. H. 1997; 36: PubMed Scopus Google Scholar). that is the that an The metal is by and with protein and Nature. 1998; PubMed Scopus Google Scholar). with the of the and the metal are by both the adenylyl cyclase structure with F. L. J. PubMed Google of the and of the for of the the and of the the and both metal share in and the with the that of these the in the their in catalysis to The of the the is has that in adenylyl cyclase its in a in these Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google C. Nature. 1998; PubMed Scopus Google Scholar). catalysis is the other for catalysis J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar, S.-Z. Huang Z.-H. Tang W.-J. J. 1997; PubMed Scopus Google for the mechanism of adenylyl by and is from the structure Nature. 1998; PubMed Scopus Google and the mechanism is from that of Nature. 1998; PubMed Scopus Google Scholar). C1 are and C2 are is for by are the two and and the and the is with the of its other are and of both and catalysis are C1 and is to understanding of adenylyl cyclase catalytic that that the of the C1 and C2 domains the structure of the and catalytic structure of the catalytic core is in two that of the (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google Scholar) and that of the and J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar). The two structures by a of the C1 to the C2 in the The catalytic elements from the two domains to each The the two by in in the two by of two by the of Despite of these are the is that the two of the adenylyl cyclase are of into by adenylyl cyclases are by and by of free are to physiological to for these enzymes by with the is the is a free to enzymes to and physiological of and adenylyl cyclase by free has PubMed Scopus Google and the of a in the of these isoforms has K. 1997; PubMed Scopus Google by P-site are a of of adenylyl cyclase all contain a L. J. 1996; PubMed Scopus Google Scholar). The a and are the L. J. 1996; PubMed Scopus Google Scholar, L. J. 1996; PubMed Scopus Google Scholar, L. J. 1998; PubMed Scopus Google Scholar). P-site is adenylyl cyclase is P-site is to that enzyme P-site are with to the with the in the C.W. Gilman A.G. J. 1997; PubMed Scopus Google Scholar). P-site are cyclases that are in all other by the adenylyl cyclases R.K. J.J.G. Sprang S.R. Gilman A.G. J. 1998; PubMed Scopus Google Scholar). P-site to the through adenylyl cyclases in P-site and a physiological for of has L. G. E. J. J. 1997; PubMed Scopus Google by is a of all the mammalian adenylyl cyclases is an of of the adenylyl cyclase by to other of adenylyl cyclase to the catalytic core the of the that the J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar, Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar). the enzyme by the two domains in the core a of and that are the two domains (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google Scholar). adenylyl cyclase is to of a and a in the these are by the by well other adenylyl cyclases S.-Z. Huang Z.-H. R.K. Tang W.-J. Mol. Pharmacol. 1998; PubMed Scopus Google is a that the The are in and in The of a in a protein is in the of that a led to the that an of adenylyl by G-protein mammalian adenylyl cyclases are and by the G-protein is with to to a the of the by and of C2 and by the of C1 J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar, S.-Z. Huang Z.-H. Hurley J.H. Tang W.-J. J. 1997; PubMed Scopus Google Scholar, G. J. 1998; PubMed Scopus Google Scholar). is of C1 and C2 forskolin, its the C1 is is to C1 and a for S.-Z. Huang Z.-H. Hurley J.H. Tang W.-J. J. 1997; PubMed Scopus Google Scholar). is to a that The of the catalytic into their is the of a by the C1 from its J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google adenylyl cyclase and and led to the that to the adenylyl cyclase catalytic core a to the J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar, S.-Z. Huang Z.-H. Hurley J.H. Tang W.-J. J. 1997; PubMed Scopus Google Scholar). that the by and of C1 is the primary for of to C.W. J.J.G. Sprang S.R. Gilman A.G. J. 1998; PubMed Scopus Google Scholar). The inhibitory mechanism a of the C1 in the that by adenylyl adenylyl cyclase is by is of the of has J. J.H. J. Science. 1995; 268: PubMed Scopus Google Scholar). The a and and the first of (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google Scholar). The is the with with regions of adenylyl cyclase The of was predicted to with adenylyl cyclase H. Gilman A.G. J. PubMed Google Scholar, Cell. PubMed Scopus (160) Google with the catalytic was in the of the adenylyl cyclase has the is the C2 K. C. 1997; PubMed Scopus Google in of these by I adenylyl cyclase by to a the L. F. E. PubMed Scopus (139) Google Scholar, Storm D.R. J. 268: PubMed Google Scholar). The mechanism is other enzymes are a is that will an the core and the by kinase adenylyl cyclase by C. Res. 1997; PubMed Scopus Google Scholar). is a to for protein kinase Reed R.R. J. 1995; PubMed Scopus Google Scholar). is the of the a that is in the structure the of the in the the of the to the kinase adenylyl cyclase by J. G. Storm D.R. J. 1996; PubMed Scopus Google Scholar). is the of the its with kinase in the of Y. J. G. 1997; PubMed Scopus Google Scholar) and to a for kinase I adenylyl cyclase in its and by with the J. Storm D.R. Mol. Cell. 1996; PubMed Scopus Google and of has the core structure of adenylyl The core of two The all two metal to The and other catalytic are by the other to to The of the of mammalian adenylyl and forskolin, to the and in a and The the the protein to the of the to the of the catalytic protein kinase to protein kinase The the of mammalian adenylyl cyclases and a new for a understanding of in understanding the structure and function of the C1a and C2 regions has by the of adenylyl for the transmembrane M1 and a (8Krupinski J. Coussen F. Bakalyar H. Tang W.-J. Feinstein P.G. Orth K. Slaughter C. Reed R.R. Gilman A.G. Science. 1989; 244: 1558-1564Crossref PubMed Scopus (505) Google membrane D. G. Storm D.R. J. 1995; PubMed Scopus Google Scholar, D.M.F. J. 1998; PubMed Scopus Google N. D.M.F. J. 1998; Scopus Google Scholar) to of a major are for with in the catalytic core in the is a has the of in the structure and of adenylyl cyclase to the of cAMP The has that are P-site The of are many the of these will by with cyclase isoforms provide new to in how a a adenylyl cyclase in the context of many The discovery of 3′,5′-cyclic adenosine monophosphate (cAMP) in the late 1950s by Sutherland and co-workers was the pivotal event that led to our current paradigm of hormone signaling through second messengers. Despite the subsequent discovery of many other second messengers, cAMP has never left center stage. The adenylyl cyclases are the family of enzymes that synthesize cAMP (1Sunahara R.K. Dessauer C.W. Gilman A.G. Annu. Rev. Pharmacol. Toxicol. 1996; 36: 461-480Crossref PubMed Scopus (732) Google Scholar, 2Xia Z.G. Storm D.R. Curr. Opin. Neurobiol. 1997; 7: 391-396Crossref PubMed Scopus (122) Google Scholar, 3Hanoune J. Pouille Y. Tzavara E. Shen T.S. Lipskaya L. Miyamoto N. Suzuki Y. Defer N. Mol. Cell. Endocrinol. 1997; 128: 179-194Crossref PubMed Scopus (139) Google Scholar, 4Cooper D.M.F. Adv. Second Messenger Phosphoprotein Res. 1998; : 32Google Scholar, 5Tang W.-J. Hurley J.H. Mol. Pharmacol. 1998; 54: 231-240Crossref PubMed Scopus (160) Google Scholar). in determining the first structures of the mammalian adenylyl cyclase catalytic core (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google Scholar, 7Tesmer J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar) provide a new context for understanding the action of many regulators, both physiological and pharmacological: free metal ions, P-site inhibitors, forskolin, G-proteins, Ca2+/calmodulin, and protein phosphorylation. Understanding the catalytic mechanism of an enzyme is a prerequisite to understanding its regulation. Here I will describe the essentials of catalysis and then consider how these elements are controlled by each of the major of Adenylyl CyclaseThe nine cloned isoforms of mammalian adenylyl cyclase share a primary structure consisting of two transmembrane regions, M1 and M2, and two cytoplasmic regions, C1 and C2 (8Krupinski J. Coussen F. Bakalyar H. Tang W.-J. Feinstein P.G. Orth K. Slaughter C. Reed R.R. Gilman A.G. Science. 1989; 244: 1558-1564Crossref PubMed Scopus (505) Google Scholar) (Fig.1). The transmembrane regions each contain six predicted membrane-spanning helices. The function of M1 and M2, aside from membrane localization, is unknown despite their topological analogy to transporters. The C1 and C2 regions are subdivided into C1a and C1b; and C2a and C2b. The C1a and C2a are well conserved, homologous to each other, and contain all of the catalytic apparatus (9Tang W.-J. Gilman A.G. Science. 1995; 268: 1769-1772Crossref PubMed Scopus (165) Google Scholar). C1a and C2a domains heterodimerize with each other in solution (10Yan S.-Z. Hahn D. Huang Z.-H. Tang W.-J. J. 1996; PubMed Scopus Google Scholar, Gilman A.G. Dessauer C.W. 1996; PubMed Scopus Google Scholar). domains from isoforms The is and The is in isoforms and C2 and C2a are to structure of the adenylyl cyclase C2 a with two C2 in a (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google Scholar). the two in the center of the to in the The is that the the The is the is to the domains of the I and Nature. 1997; PubMed Scopus Google Scholar, J. Liu Y. Ruoho A.E. G. Hurley J.H. Nature. 1997; Scopus Google C1a and C2 in a that is in structure to the C2 with in J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar). The is of the The by C.W. Gilman A.G. J. 1997; PubMed Scopus Google is the The is the by by both C1a and the is the two of two catalytic domains in the is an prerequisite of catalytic The of mammalian adenylyl cyclases the of C1a and is the for many other cyclases Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, J.H. Curr. Opin. 1998; PubMed Scopus Google Scholar). membrane cyclases and many of mammalian adenylyl cyclases are The mammalian C2 has (9Tang W.-J. Gilman A.G. Science. 1995; 268: 1769-1772Crossref PubMed Scopus (165) Google Scholar, G. Liu Y. J. Tang W.-J. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, Tang W.-J. C. 1998; PubMed Scopus Google by many of of the of two catalytic to the The nine cloned isoforms of mammalian adenylyl cyclase share a primary structure consisting of two transmembrane regions, M1 and M2, and two cytoplasmic regions, C1 and C2 (8Krupinski J. Coussen F. Bakalyar H. Tang W.-J. Feinstein P.G. Orth K. Slaughter C. Reed R.R. Gilman A.G. Science. 1989; 244: 1558-1564Crossref PubMed Scopus (505) Google Scholar) (Fig.1). The transmembrane regions each contain six predicted membrane-spanning helices. The function of M1 and M2, aside from membrane localization, is unknown despite their topological analogy to transporters. The C1 and C2 regions are subdivided into C1a and C1b; and C2a and C2b. The C1a and C2a are well conserved, homologous to each other, and contain all of the catalytic apparatus (9Tang W.-J. Gilman A.G. Science. 1995; 268: 1769-1772Crossref PubMed Scopus (165) Google Scholar). C1a and C2a domains heterodimerize with each other in solution (10Yan S.-Z. Hahn D. Huang Z.-H. Tang W.-J. J. 1996; PubMed Scopus Google Scholar, Gilman A.G. Dessauer C.W. 1996; PubMed Scopus Google Scholar). domains from isoforms The is and The is in isoforms and C2 and C2a are to The structure of the adenylyl cyclase C2 a with two C2 in a (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google Scholar). the two in the center of the to in the The is that the the The is the is to the domains of the I and Nature. 1997; PubMed Scopus Google Scholar, J. Liu Y. Ruoho A.E. G. Hurley J.H. Nature. 1997; Scopus Google Scholar). The C1a and C2 in a that is in structure to the C2 with in J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar). The is of the The by C.W. Gilman A.G. J. 1997; PubMed Scopus Google is the The is the by by both C1a and the is the two of two catalytic domains in the is an prerequisite of catalytic The of mammalian adenylyl cyclases the of C1a and is the for many other cyclases Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, J.H. Curr. Opin. 1998; PubMed Scopus Google Scholar). membrane cyclases and many of mammalian adenylyl cyclases are The mammalian C2 has (9Tang W.-J. Gilman A.G. Science. 1995; 268: 1769-1772Crossref PubMed Scopus (165) Google Scholar, G. Liu Y. J. Tang W.-J. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, Tang W.-J. C. 1998; PubMed Scopus Google by many of of the of two catalytic to the and has by the structure of the P-site J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google and Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, W.-J. Gilman A.G. 1995; PubMed Scopus Google Scholar, S.-Z. Huang Z.-H. Tang W.-J. J. 1997; PubMed Scopus Google Scholar, Hurley J.H. Hurley 1998; PubMed Scopus Google Scholar, R.K. J.J.G. Sprang S.R. Gilman A.G. J. 1998; PubMed Scopus Google Scholar). the is is for and from C2 with the and of the of C1 a by the of these the of adenylyl into a cyclase R.K. J.J.G. Sprang S.R. Gilman A.G. J. 1998; PubMed Scopus Google Scholar). is of a that to the and cyclases into adenylyl cyclases by their and to their adenylyl cyclase and Hurley J.H. Hurley 1998; PubMed Scopus Google Scholar, R.K. J.J.G. Sprang S.R. Gilman A.G. J. 1998; PubMed Scopus Google is by that the and by with are by are by and The is of a the that is of an (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar). The has by the structure of the P-site J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google and Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, W.-J. Gilman A.G. 1995; PubMed Scopus Google Scholar, S.-Z. Huang Z.-H. Tang W.-J. J. 1997; PubMed Scopus Google Scholar, Hurley J.H. Hurley 1998; PubMed Scopus Google Scholar, R.K. J.J.G. Sprang S.R. Gilman A.G. J. 1998; PubMed Scopus Google Scholar). the is is for and from C2 with the and of the of C1 a by the of these the of adenylyl into a cyclase R.K. J.J.G. Sprang S.R. Gilman A.G. J. 1998; PubMed Scopus Google Scholar). is of a that to the and cyclases into adenylyl cyclases by their and to their adenylyl cyclase and Hurley J.H. Hurley 1998; PubMed Scopus Google Scholar, R.K. J.J.G. Sprang S.R. Gilman A.G. J. 1998; PubMed Scopus Google Scholar). The is by that the and by with are by are by and The is of a the that is of an (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar). of two Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, W.-J. Gilman A.G. 1995; PubMed Scopus Google Scholar). The P-site a with both of J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar). is for a mechanism J. J. 1995; PubMed Scopus Google Scholar, G. D. J. 1998; PubMed Scopus Google Scholar). free the other a with for the The the of a the of a the of a its to Nature. 1998; PubMed Scopus Google Scholar, C. Nature. 1998; PubMed Scopus Google Scholar, J. H. 1997; 36: PubMed Scopus Google Scholar, Nature. 1998; PubMed Scopus Google a for the of two in the adenylyl cyclase The metal to the in the adenylyl cyclase all in a Nature. 1998; PubMed Scopus Google Scholar, J. H. 1997; 36: PubMed Scopus Google Scholar). that is the that an The metal is by and with protein and Nature. 1998; PubMed Scopus Google Scholar). with the of the and the metal are by both the adenylyl cyclase structure with F. L. J. PubMed Google Scholar). The of two Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google Scholar, W.-J. Gilman A.G. 1995; PubMed Scopus Google Scholar). The P-site a with both of J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar). is for a mechanism J. J. 1995; PubMed Scopus Google Scholar, G. D. J. 1998; PubMed Scopus Google Scholar). free the other a with for the The the of a the of a the of a its to Nature. 1998; PubMed Scopus Google Scholar, C. Nature. 1998; PubMed Scopus Google Scholar, J. H. 1997; 36: PubMed Scopus Google Scholar, Nature. 1998; PubMed Scopus Google a for the of two in the adenylyl cyclase The metal to the in the adenylyl cyclase all in a Nature. 1998; PubMed Scopus Google Scholar, J. H. 1997; 36: PubMed Scopus Google Scholar). that is the that an The metal is by and with protein and Nature. 1998; PubMed Scopus Google Scholar). with the of the and the metal are by both the adenylyl cyclase structure with F. L. J. PubMed Google Scholar). of the and of the for of the the and of the the and both metal share in and the with the that of these the in the their in catalysis to The of the the is has that in adenylyl cyclase its in a in these Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google C. Nature. 1998; PubMed Scopus Google Scholar). catalysis is the other for catalysis J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar, S.-Z. Huang Z.-H. Tang W.-J. J. 1997; PubMed Scopus Google Scholar). the and of the for of the the and of the the and both metal share in and the with the that of these the in the their in catalysis to The of the the is has that in adenylyl cyclase its in a in these Y. Ruoho A.E. Hurley J.H. 1997; PubMed Scopus Google C. Nature. 1998; PubMed Scopus Google Scholar). catalysis is the other for catalysis J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar, S.-Z. Huang Z.-H. Tang W.-J. J. 1997; PubMed Scopus Google Scholar). and of both and catalysis are C1 and is to understanding of adenylyl cyclase catalytic that that the of the C1 and C2 domains the structure of the and catalytic structure of the catalytic core is in two that of the (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google Scholar) and that of the and J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar). The two structures by a of the C1 to the C2 in the The catalytic elements from the two domains to each The the two by in in the two by of two by the of Despite of these are the is that the two of the adenylyl cyclase are of into The of both and catalysis are C1 and is to understanding of adenylyl cyclase catalytic that that the of the C1 and C2 domains the structure of the and catalytic The structure of the catalytic core is in two that of the (6Zhang G. Liu Y. Ruoho A.E. Hurley J.H. Nature. 1997; 386: 247-253Crossref PubMed Scopus (323) Google Scholar) and that of the and J.J.G. Sunahara R.K. Gilman A.G. Sprang S.R. Science. 1997; 278: 1907-1916Crossref PubMed Scopus (670) Google Scholar). 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