Interaction sites between the Slo1 pore and the NH2 terminus of the beta2 subunit, probed with a three-residue sensor.
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.
Li
Hui
H
Institute of Biochemistry and Biophysics, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
Yao
Jing
J
Tong
Xiaotian
X
Guo
Zhaohua
Z
Wu
Ying
Y
Sun
Liang
L
Pan
Na
N
Wu
Houming
H
Xu
Tao
T
Ding
Jiuping
J
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004252:DNA Mutational Analysis; D006801:Humans; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051038:Large-Conductance Calcium-Activated Potassium Channel beta Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D018408:Patch-Clamp Techniques; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D014982:Xenopus laevis
C465449:Kcnma1 protein, mouse; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051038:Large-Conductance Calcium-Activated Potassium Channel beta Subunits