6nfu
From Proteopedia
Structure of the KcsA-G77A mutant or the 2,4-ion bound configuration of a K+ channel selectivity filter.
Structural highlights
FunctionKCSA_STRLI Acts as a pH-gated potassium ion channel; changing the cytosolic pH from 7 to 4 opens the channel, although it is not clear if this is the physiological stimulus for channel opening. Monovalent cation preference is K(+) > Rb(+) > NH4(+) >> Na(+) > Li(+).[1] Publication Abstract from PubMedHere, we present the atomic resolution crystallographic structure, the function, and the ion-binding properties of the KcsA mutants, G77A and G77C, that stabilize the 2,4-ion-bound configuration (i.e., water, K(+), water, K(+)-ion-bound configuration) of the K(+) channel's selectivity filter. A full functional and thermodynamic characterization of the G77A mutant revealed wild-type-like ion selectivity and apparent K(+)-binding affinity, in addition to showing a lack of C-type inactivation gating and a marked reduction in its single-channel conductance. These structures validate, from a structural point of view, the notion that 2 isoenergetic ion-bound configurations coexist within a K(+) channel's selectivity filter, which fully agrees with the water-K(+)-ion-coupled transport detected by streaming potential measurements. Structure, function, and ion-binding properties of a K(+) channel stabilized in the 2,4-ion-bound configuration.,Tilegenova C, Cortes DM, Jahovic N, Hardy E, Hariharan P, Guan L, Cuello LG Proc Natl Acad Sci U S A. 2019 Aug 6. pii: 1901888116. doi:, 10.1073/pnas.1901888116. PMID:31387976[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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