1jba
From Proteopedia
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UNMYRISTOYLATED GCAP-2 WITH THREE CALCIUM IONS BOUND
Overview
Guanylyl cyclase activating protein-2 (GCAP-2) is a Ca2+-sensitive, regulator of phototransduction in retinal photoreceptor cells. GCAP-2, activates retinal guanylyl cyclases at low Ca2+ concentration (<100 nM), and inhibits them at high Ca2+ (>500 nM). The light-induced lowering of, the Ca2+ level from approximately 500 nM in the dark to approximately 50, nM following illumination is known to play a key role in visual recovery, and adaptation. We report here the three-dimensional structure of, unmyristoylated GCAP-2 with three bound Ca2+ ions as determined by nuclear, magnetic resonance spectroscopy of recombinant, isotopically labeled, protein. GCAP-2 contains four EF-hand motifs arranged in a compact tandem, array like that seen previously in recoverin. The root mean square, deviation of the main chain atoms in the EF-hand regions is 2.2 A in, comparing the Ca2+-bound structures of GCAP-2 and recoverin. EF-1, as in, recoverin, does not bind calcium because it contains a disabling Cys-Pro, sequence. GCAP-2 differs from recoverin in that the calcium ion binds to, EF-4 in addition to EF-2 and EF-3. A prominent exposed patch of, hydrophobic residues formed by EF-1 and EF-2 (Leu24, Trp27, Phe31, Phe45, Phe48, Phe49, Tyr81, Val82, Leu85, and Leu89) may serve as a, target-binding site for the transmission of calcium signals to guanylyl, cyclase.
About this Structure
1JBA is a Single protein structure of sequence from Bos taurus with CA as ligand. Active as Guanylate cyclase, with EC number 4.6.1.2 Full crystallographic information is available from OCA.
Reference
Three-dimensional structure of guanylyl cyclase activating protein-2, a calcium-sensitive modulator of photoreceptor guanylyl cyclases., Ames JB, Dizhoor AM, Ikura M, Palczewski K, Stryer L, J Biol Chem. 1999 Jul 2;274(27):19329-37. PMID:10383444
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