2ygg
Complex of CaMBR and CaM
Structural highlights
FunctionSL9A1_HUMAN Involved in pH regulation to eliminate acids generated by active metabolism or to counter adverse environmental conditions. Major proton extruding system driven by the inward sodium ion chemical gradient. Plays an important role in signal transduction.[1] [2] [3] Publication Abstract from PubMedThe ubiquitous mammalian Na(+)/H(+)-exchanger NHE1 has critical functions in regulating intracellular pH, salt concentration and cellular volume. The regulatory C-terminal domain of NHE1 is linked to the ion-translocating N-terminal membrane domain, and acts as a scaffold for signalling complexes. A major interaction partner is calmodulin (CaM), which binds to two neighbouring regions of NHE1 in a strongly Ca(2+) dependent manner. Upon CaM binding, NHE1 is activated by a shift in sensitivity towards alkaline intracellular pH. Here we report the 2.23 A crystal structure of the NHE1 CaM binding region (NHE1(CaMBR)) in complex with CaM and Ca(2+). The C- and N-lobes of CaM bind the first and second helix of NHE1(CaMBR), respectively. Both the NHE1 helices and Ca(2+)-bound CaM are elongated, as confirmed by small angle X-ray scattering analysis. Our X-ray structure sheds new light on the molecular mechanisms of the phosphorylation-dependent regulation of NHE1 and enables us to propose a model of how Ca(2+) regulates NHE1 activity. Structure of human Na+/H+ exchanger NHE1 regulatory region in complex with CaM and Ca2+,Koester S, Pavkov-Keller T, Kuehlbrandt W, Yildiz O J Biol Chem. 2011 Sep 19. PMID:21931166[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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