1tl7: Difference between revisions

[[Image:1tl7.gif|left|200px]]<br /><applet load="1tl7" size="350" color="white" frame="true" align="right" spinBox="true"  

Membrane-bound mammalian adenylyl cyclase (mAC) catalyzes the synthesis of intracellular cyclic AMP from ATP and is activated by stimulatory G protein alpha subunits (Galpha(s)) and by forskolin (FSK). mACs are inhibited with high potency by 2 '(3')-O-(N-methylanthraniloyl) (MANT)-substituted nucleotides. In this study, the crystal structures of the complex between Galpha(s).GTPgammaS and the catalytic C1 and C2 domains from type V and type II mAC (VC1.IIC2), bound to FSK and either MANT-GTP.Mg(2+) or MANT-GTP.Mn(2+) have been determined. MANT-GTP coordinates two metal ions and occupies the same position in the catalytic site as P-site inhibitors and substrate analogs. However, the orientation of the guanine ring is reversed relative to that of the adenine ring. The MANT fluorophore resides in a hydrophobic pocket at the interface between the VC1 and IIC2 domains and prevents mAC from undergoing the "open" to "closed" domain rearrangement. The K(i) of MANT-GTP for inhibition of VC1.IIC2 is lower in the presence of mAC activators and lower in the presence of Mn(2+) compared with Mg(2+), indicating that the inhibitor binds more tightly to the catalytically most active form of the enzyme. Fluorescence resonance energy transfer-stimulated emission from the MANT fluorophore upon excitation of Trp-1020 in the MANT-binding pocket of IIC2 is also stronger in the presence of FSK. Mutational analysis of two non-conserved amino acids in the MANT-binding pocket suggests that residues outside of the binding site influence isoform selectivity toward MANT-GTP.

1TL7 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus], [http://en.wikipedia.org/wiki/Canis_lupus_familiaris Canis lupus familiaris] and [http://en.wikipedia.org/wiki/Rattus_norvegicus Rattus norvegicus] with <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=CL:'>CL</scene>, <scene name='pdbligand=MN:'>MN</scene>, <scene name='pdbligand=GSP:'>GSP</scene>, <scene name='pdbligand=FOK:'>FOK</scene> and <scene name='pdbligand=ONM:'>ONM</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Adenylate_cyclase Adenylate cyclase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.6.1.1 4.6.1.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TL7 OCA].  

[[Category: Mou, T C.]]

[[Category: Seifert, R J.]]

[[Category: Sprang, S R.]]

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