Immunohistochemical study of a rat membrane protein which induces a selective potassium permeation: its localization in the apical membrane portion of epithelial cells.
J Membr Biol
; 113(1): 39-47, 1990 Jan.
Article
en En
| MEDLINE
| ID: mdl-2154581
We previously reported a novel rat membrane protein that exhibits a voltage-dependent potassium channel activity on the basis of molecular cloning combined with an electrophysiological assay. This protein, termed IsK protein, is small and different from the conventional potassium channel proteins but induces selective permeation of potassium ions on its expression in Xenopus oocytes. In this investigation, we examined cellular localization of rat IsK protein by preparing three different types of antibody that specifically reacts with a distinct part of rat IsK protein. Immunohistochemical analysis using these antibody preparations demonstrated that rat IsK protein is confined to the apical membrane portion of epithelial cells in the proximal tubule of the kidney, the submandibular duct and the uterine endometrium. The observed tissue distribution of rat IsK protein was consistent with that of the IsK protein mRNA determined by blot hybridization analysis. In epithelial cells, the sodium, potassium-ATPase pump in the basolateral membrane generates a sodium gradient across the epithelial cell and allows sodium ions to enter the cell through the apical membrane. Thus, taking into account the cellular localization of the IsK protein, together with its electrophysiological properties, we discussed a possible function of the IsK protein, namely that this protein is involved in potassium permeation in the apical membrane of epithelial cells through the depolarizing effect of sodium entry.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Potasio
/
Canales de Potasio
/
Membrana Celular
/
Permeabilidad de la Membrana Celular
/
Canales de Potasio con Entrada de Voltaje
/
Proteínas de la Membrana
Límite:
Animals
Idioma:
En
Revista:
J Membr Biol
Año:
1990
Tipo del documento:
Article
País de afiliación:
Japón
Pais de publicación:
Estados Unidos