2hmw
From Proteopedia
Square-shaped octameric ring structure of an RCK domain with ATP bound
Structural highlights
FunctionKTRA_BACSU Catalytic subunit of the KtrAB potassium uptake transporter. The 2 major potassium transporter complexes KtrAB and KtrCD confer resistance to both suddenly imposed and prolonged osmotic stress.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe KtrAB ion transporter is a complex of the KtrB membrane protein and KtrA, an RCK domain. RCK domains regulate eukaryotic and prokaryotic membrane proteins involved in K(+) transport. Conflicting functional models have proposed two different oligomeric arrangements for RCK domains, tetramer versus octamer. Our results for the KtrAB RCK domain clearly show an octamer in solution and in the crystal. We determined the structure of this protein in three different octameric ring conformations that resemble the RCK-domain octamer observed in the MthK potassium channel but show striking differences in size and symmetry. We present experimental evidence for the association between one RCK octameric ring and two KtrB membrane proteins. These results provide insights into the quaternary organization of the KtrAB transporter and its mechanism of activation and show that the RCK-domain octameric ring model is generally applicable to other ion-transport systems. The RCK domain of the KtrAB K+ transporter: multiple conformations of an octameric ring.,Albright RA, Ibar JL, Kim CU, Gruner SM, Morais-Cabral JH Cell. 2006 Sep 22;126(6):1147-59. PMID:16990138[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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