2agv
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Crystal structure of the SR CA2+-ATPASE with BHQ and TG
OverviewOverview
Ca(2+)-ATPase of sarcoplasmic reticulum is an ATP-powered Ca(2+) pump but, also a H(+) pump in the opposite direction with no demonstrated functional, role. Here, we report a 2.4-A-resolution crystal structure of the, Ca(2+)-ATPase in the absence of Ca(2+) stabilized by two inhibitors, dibutyldihydroxybenzene, which bridges two transmembrane helices, and, thapsigargin, also bound in the membrane region. Now visualized are water, and several phospholipid molecules, one of which occupies a cleft between, two transmembrane helices. Atomic models of the Ca(2+) binding sites with, explicit hydrogens derived by continuum electrostatic calculations show, how water and protons fill the space and compensate charge imbalance, created by Ca(2+)-release. They suggest that H(+) countertransport is a, consequence of a requirement for maintaining structural integrity of the, empty Ca(2+)-binding sites. For this reason, cation countertransport is, probably mandatory for all P-type ATPases and possibly accompanies, transport of water as well.
About this StructureAbout this Structure
2AGV is a Single protein structure of sequence from Oryctolagus cuniculus with NA, TG1, BHQ and PTY as ligands. Active as Calcium-transporting ATPase, with EC number 3.6.3.8 Full crystallographic information is available from OCA.
ReferenceReference
Structural role of countertransport revealed in Ca(2+) pump crystal structure in the absence of Ca(2+)., Obara K, Miyashita N, Xu C, Toyoshima I, Sugita Y, Inesi G, Toyoshima C, Proc Natl Acad Sci U S A. 2005 Oct 11;102(41):14489-96. Epub 2005 Sep 6. PMID:16150713
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