Structural highlights
FunctionAT1B1_PIG This is the non-catalytic component of the active enzyme, which catalyzes the hydrolysis of ATP coupled with the exchange of Na(+) and K(+) ions across the plasma membrane. The beta subunit regulates, through assembly of alpha/beta heterodimers, the number of sodium pumps transported to the plasma membrane. Publication Abstract from PubMedNa(+) ,K(+) -ATPase (NKA) plays a pivotal role in establishing electrochemical gradients for Na(+) and K(+) across the cell membrane by alternating between the E1 (showing high affinity for Na(+) and low affinity for K(+) ) and E2 (low affinity to Na(+) and high affinity to K(+) ) forms. Presented here are two crystal structures of NKA in E1.Mg(2+) and E1.3Na(+) states at 2.9 and 2.8 A resolution, respectively. These two E1 structures fill a gap in our description of the NKA reaction cycle based on the atomic structures. We describe how NKA converts the K(+) -bound E2.2K(+) form to an E1 (E1.Mg(2+) ) form, which allows high-affinity Na(+) binding, eventually closing the cytoplasmic gate (in E1 ~ P.ADP.3Na(+) ) after binding three Na(+) , while keeping the extracellular ion pathway sealed. We now understand previously unknown functional roles for several parts of NKA and that NKA uses even the lipid bilayer for gating the ion pathway. Crystal structures of Na(+) ,K(+) -ATPase reveal the mechanism that converts the K(+) -bound form to Na(+) -bound form and opens and closes the cytoplasmic gate.,Kanai R, Vilsen B, Cornelius F, Toyoshima C FEBS Lett. 2023 Aug;597(15):1957-1976. doi: 10.1002/1873-3468.14689. Epub 2023 , Jul 6. PMID:37357620[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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