Reinterpretation of the ractk1 k+ channel.
Shmukler, B., T. Sun, C. Brugnara, and S. L. Alper.
Molecular Medicine and Renal Units, Beth Israel Hospital; Div. of
Laboratory Medicine, The Children's Hospital; Depts. of Medicine,
Pathology, and Cell Biology, Harvard Medical School, Boston, MA
APStracts 3:0326C, 1996.
Suzuki et al. (1) reported a novel K+ channel cDNA sequence (Genbank
D16216) cloned by expression from a rabbit kidney cortical collecting
duct cell library. This channel, named RACTK1, was unrelated in
sequence to any other cloned K+ channel, though its hydropathy plot
resembled that of an inward rectifier K+ channel. Most notably, the
deduced amino acid sequence between putative transmembrane spans M1
and M2 lacked any sequence easily recognizable as a K+ selective
pore, even when aligned differently with known K+ channel pore
regions by Sutcliffe and Stanfield (2). However, microinjection of
RACTK1 cRNA into CHO cells conferred a pH-sensitive, inwardly
rectifying K+ current on at least 9 cells of 500 tested (1). Suzuki
et al. subsequently contributed to the database a very highly
homologous human RACTK1 cDNA sequence (Genbank U33839).
Received 10 June 1996; accepted in final form 27 August 1996.
APS Manuscript Number C325-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996