Title: Interaction sites between the Slo1 pore and the NH2 terminus of the beta2 subunit, probed with a three-residue sensor.

Authors: Hui Li, Jing Yao, Xiaotian Tong, Zhaohua Guo, Ying Wu, Liang Sun, Na Pan, Houming Wu, Tao Xu, Jiuping Ding

Journal, date & volume: J. Biol. Chem., 2007 Jun 15 , 282, 17720-8

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/17430898

Abstract
Calcium- and voltage-gated (BK) K(+) channels encoded by Slo1 play an essential role in nervous systems. Although it shares many common features with voltage-dependent K(V) channels, the BK channel exhibits differences in gating and inactivation. Using a mutant in which FWI replaces three residues (FIW) in the NH(2) terminus of wild-type beta2-subunits, in conjunction with alanine-scanning mutagenesis of the Slo1 S6 segment, we identify that the NH(2) terminus of beta2-subunits interacts with the residues near the cytosolic superficial mouth of BK channels during inactivation. The cytosolic blockers did not share the sites with NH(2) terminus of beta2-subunits. A novel blocking-inactivating scheme was proposed to account for the observed non-competition inactivation. Our results also suggest that the residue Ile-323 plays a dual role in interacting with the NH(2) terminus of beta2-subunits and modulating the gating of BK channels.