1xp5
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(New page: 200px<br /><applet load="1xp5" size="450" color="white" frame="true" align="right" spinBox="true" caption="1xp5, resolution 3.0Å" /> '''Structure Of The (Sr)...)
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Revision as of 04:07, 21 November 2007
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Structure Of The (Sr)Ca2+-ATPase E2-AlF4- Form
Overview
P-type ATPases extract energy by hydrolysis of adenosine triphosphate, (ATP) in two steps, formation and breakdown of a covalent phosphoenzyme, intermediate. This process drives active transport and countertransport of, the cation pumps. We have determined the crystal structure of rabbit, sarcoplasmic reticulum Ca2+ adenosine triphosphatase in complex with, aluminum fluoride, which mimics the transition state of hydrolysis of the, counterion-bound (protonated) phosphoenzyme. On the basis of structural, analysis and biochemical data, we find this form to represent an occluded, state of the proton counterions. Hydrolysis is catalyzed by the conserved, Thr-Gly-Glu-Ser motif, and it exploits an associative nucleophilic, reaction mechanism of the same type as phosphoryl transfer from ATP. On, this basis, we propose a general mechanism of occluded transition states, of Ca2+ transport and H+ countertransport coupled to phosphorylation and, dephosphorylation, respectively.
About this Structure
1XP5 is a Single protein structure of sequence from Oryctolagus cuniculus with MG, ALF, K and TG1 as ligands. Active as Calcium-transporting ATPase, with EC number 3.6.3.8 Full crystallographic information is available from OCA.
Reference
Dephosphorylation of the calcium pump coupled to counterion occlusion., Olesen C, Sorensen TL, Nielsen RC, Moller JV, Nissen P, Science. 2004 Dec 24;306(5705):2251-5. PMID:15618517
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