Publication Abstract from PubMed
The sodium-potassium pump (Na(+),K(+)-ATPase) is responsible for establishing Na(+) and K(+) concentration gradients across the plasma membrane and therefore plays an essential role in, for instance, generating action potentials. Cardiac glycosides, prescribed for congestive heart failure for more than 2 centuries, are efficient inhibitors of this ATPase. Here we describe a crystal structure of Na(+),K(+)-ATPase with bound ouabain, a representative cardiac glycoside, at 2.8 A resolution in a state analogous to E2.2K(+).Pi. Ouabain is deeply inserted into the transmembrane domain with the lactone ring very close to the bound K(+), in marked contrast to previous models. Due to antagonism between ouabain and K(+), the structure represents a low-affinity ouabain-bound state. Yet, most of the mutagenesis data obtained with the high-affinity state are readily explained by the present crystal structure, indicating that the binding site for ouabain is essentially the same. According to a homology model for the high affinity state, it is a closure of the binding cavity that confers a high affinity.
Crystal structure of the sodium-potassium pump (Na+,K+-ATPase) with bound potassium and ouabain.,Ogawa H, Shinoda T, Cornelius F, Toyoshima C Proc Natl Acad Sci U S A. 2009 Aug 18;106(33):13742-7. Epub 2009 Aug 3. PMID:19666591[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
