1S5H

Potassium Channel Kcsa-Fab Complex T75C mutant in K+

Summary for 1S5H

• Entry DOI: 10.2210/pdb1s5h/pdb
• Descriptor: ANTIBODY FAB FRAGMENT LIGHT CHAIN, ANTIBODY FAB FRAGMENT HEAVY CHAIN, Voltage-gated potassium channel, ... (7 entities in total)
• Functional Keywords: k+ channel, protein-antibody fab complex, selectivity filter, ion occupancy, membrane protein
• Biological source: Streptomyces coelicolor, Streptomyces lividans (,); More
• Total number of polymer chains: 3
• Total formula weight: 61113.57

Authors

Mackinnon, R.,Zhou, M. (deposition date: 2004-01-20, release date: 2004-05-18, Last modification date: 2024-11-20)

Primary citation

Zhou, M.,MacKinnon, R.
A mutant KcsA K(+) channel with altered conduction properties and selectivity filter ion distribution.
J.Mol.Biol., 338:839-846, 2004

PubMed Abstract: The selectivity filter of K(+) channels is comprised of a linear queue of four equal-spaced ion-binding sites spanning a distance of 12A. Each site is formed of eight oxygen atoms from the protein. The first three sites, numbered 1-3 from the extracellular side, are made of exclusively main-chain carbonyl oxygen atoms. The fourth site, closest to the intracellular side, is made of four main-chain carbonyl oxygen atoms and four threonine side-chain hydroxyl oxygen atoms. Here we characterize the effects of mutating the threonine to cysteine on the distribution of ions in the selectivity filter and on the conduction of ions through the filter. The mutation influences the occupancy of K(+) at sites 2 and 4 and it reduces the maximum rate of conduction in the limit of high K(+) concentration. The mutation does not affect the conduction of Rb(+). These results can be understood in the context of a conduction mechanism in which a pair of K ions switch between energetically balanced 1,3 and 2,4 configurations.

PubMed: 15099749
DOI: 10.1016/j.jmb.2004.03.020

Experimental method

X-RAY DIFFRACTION (2.2 Å)