3C16

Complex of GS-Alpha with the Catalytic Domains of Mammalian Adenylyl Cyclase: Complex with Adenosine-5'-Triphosphate and Ca

Summary for 3C16

• Entry DOI: 10.2210/pdb3c16/pdb
• Related: 3C14 3C15
• Descriptor: Adenylate cyclase type 5, Adenylate cyclase type 2, Guanine nucleotide-binding protein G(s) subunit alpha isoforms short, ... (10 entities in total)
• Functional Keywords: adenylyl cyclase, gsalpha, camp biosynthesis, glycoprotein, lyase, magnesium, membrane, metal-binding, phosphoprotein, transmembrane, gtp-binding, lipoprotein, nucleotide-binding, palmitate, transducer, lyase-lyase inhibitor complex, lyase/lyase inhibitor
• Biological source: Canis lupus familiaris (Dog); More
• Cellular location: Membrane; Multi-pass membrane protein: P30803 P26769; Cell membrane; Lipid-anchor (By similarity): P04896
• Total number of polymer chains: 3
• Total formula weight: 97552.89

Authors

Mou, T.-C.,Sprang, S.R. (deposition date: 2008-01-22, release date: 2009-02-03, Last modification date: 2023-08-30)

Primary citation

Mou, T.C.,Masada, N.,Cooper, D.M.,Sprang, S.R.
Structural basis for inhibition of mammalian adenylyl cyclase by calcium.
Biochemistry, 48:3387-3397, 2009

PubMed Abstract: Type V and VI mammalian adenylyl cyclases (AC5, AC6) are inhibited by Ca(2+) at both sub- and supramicromolar concentration. This inhibition may provide feedback in situations where cAMP promotes opening of Ca(2+) channels, allowing fine control of cardiac contraction and rhythmicity in cardiac tissue where AC5 and AC6 predominate. Ca(2+) inhibits the soluble AC core composed of the C1 domain of AC5 (VC1) and the C2 domain of AC2 (IIC2). As observed for holo-AC5, inhibition is biphasic, showing "high-affinity" (K(i) = approximately 0.4 microM) and "low-affinity" (K(i) = approximately 100 microM) modes of inhibition. At micromolar concentration, Ca(2+) inhibition is nonexclusive with respect to pyrophosphate (PP(i)), a noncompetitive inhibitor with respect to ATP, but at >100 microM Ca(2+), inhibition appears to be exclusive with respect to PP(i). The 3.0 A resolution structure of Galphas.GTPgammaS/forskolin-activated VC1:IIC2 crystals soaked in the presence of ATPalphaS and 8 microM free Ca(2+) contains a single, loosely coordinated metal ion. ATP soaked into VC1:IIC2 crystals in the presence of 1.5 mM Ca(2+) is not cyclized, and two calcium ions are observed in the 2.9 A resolution structure of the complex. In both of the latter complexes VC1:IIC2 adopts the "open", catalytically inactive conformation characteristic of the apoenzyme, in contrast to the "closed", active conformation seen in the presence of ATP analogues and Mg(2+) or Mn(2+). Structures of the pyrophosphate (PP(i)) complex with 10 mM Mg(2+) (2.8 A) or 2 mM Ca(2+) (2.7 A) also adopt the open conformation, indicating that the closed to open transition occurs after cAMP release. In the latter complexes, Ca(2+) and Mg(2+) bind only to the high-affinity "B" metal site associated with substrate/product stabilization. Ca(2+) thus stabilizes the inactive conformation in both ATP- and PP(i)-bound states.

PubMed: 19243146
DOI: 10.1021/bi802122k

Experimental method

X-RAY DIFFRACTION (2.87 Å)