Structural highlights
Function
[KCSA_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 PubMed
Using a constitutively active channel mutant, we solved the structure of full-length KcsA in the open conformation at 3.9 A. The structure reveals that the activation gate expands about 20 A, exerting a strain on the bulge helices in the C-terminal domain and generating side windows large enough to accommodate hydrated K(+) ions. Functional and spectroscopic analysis of the gating transition provides direct insight into the allosteric coupling between the activation gate and the selectivity filter. We show that the movement of the inner gate helix is transmitted to the C-terminus as a straightforward expansion, leading to an upward movement and the insertion of the top third of the bulge helix into the membrane. We suggest that by limiting the extent to which the inner gate can open, the cytoplasmic domain also modulates the level of inactivation occurring at the selectivity filter.
Mechanism of activation gating in the full-length KcsA K+ channel.,Uysal S, Cuello LG, Cortes DM, Koide S, Kossiakoff AA, Perozo E Proc Natl Acad Sci U S A. 2011 Jul 5. PMID:21730186[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Schrempf H, Schmidt O, Kummerlen R, Hinnah S, Muller D, Betzler M, Steinkamp T, Wagner R. A prokaryotic potassium ion channel with two predicted transmembrane segments from Streptomyces lividans. EMBO J. 1995 Nov 1;14(21):5170-8. PMID:7489706
- ↑ Uysal S, Cuello LG, Cortes DM, Koide S, Kossiakoff AA, Perozo E. Mechanism of activation gating in the full-length KcsA K+ channel. Proc Natl Acad Sci U S A. 2011 Jul 5. PMID:21730186 doi:10.1073/pnas.1105112108
