Nature 367, 642 - 645 (17 February 1994); doi:10.1038/367642a0

Cloning of a pH-sensitive K⁺ channel possessing two transmembrane segments

Makoto Suzuki^*, Keiko Takahashi, Masato Ikeda, Hiroshi Hayakawa, Aiichirou Ogawa, Yoshindo Kawaguchi & Osamu Sakai

^*Department of Pharmacology, Jichi Medical School, 3311-1, Minamikawachi, Kawachi, Tochigi 329-04, Japan
Internal Medicine II, Jikeikai University School of Medicine, 3-19-18, Nishishinbashi, Minatoku, Tokyo 105, Japan

THE mammalian renal collecting ducts are responsible for secreting potassium ions into the urine and are a major regulatory site for potassium homeostasis¹, in which a voltage-independent pH-sensitive K⁺ channel in the apical membrane plays a central role^2,3. Here we describe a complementary DNA encoding a novel K⁺ channel from rabbit renal cortical collecting tubule cells (RACTK1). RACTK1 has the functional characteristics of the apical K⁺-permeable channel and consists of 284 amino acids, putatively with two transmembrane segments. The sequence of RACTK1, however, shows no homology to known voltage-dependent or -independent K⁺ channels, and has a different K⁺-driving path and regulatory sites. The study of this protein should provide insight into K⁺ homeostasis and diseases of K⁺ metabolism.

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