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Título: Kvf31.2 Subunit Coexpressio n in HEK293 Cells Confers O2 Sensitivity to Kv4.2 but not to Shaker Chann els
Autor: Pérez García, María Teresa
López López, José Ramón
González, Constancio
Año del Documento: 1999
Editorial: Rockefeller University Press
Descripción: Producción Científica
Documento Fuente: Journal of Genetic Physiology, june 1999, vol. 113. p. 897-907
Resumen: Voltage-gated K+ (KV) chann els are protein complexes composed of ion-conducting integral mem- brane a subunits and cytoplasmic modulatory f3 subunits. The differe ntial expression and association of a and f3 subunits seems to contribute significantly to the complexity and hetero geneity of KV chann els in excitable cells, and their functional expression in hetero logous systems provides a tool to study their regulation at a molecular level. Here, we have studied the effects of Kvf31.2 coexpression on the properties of Shaker and Kv4.2 KV chann el a subunits, which encode rapidly inactivating A-type K+ currents, in transfecte d HEK293 cells. We found that Kvf31.2 functionally associates with these two a subunits, as well as with the endogenous KV chann els of HEK293 cells, to modulate differe nt properties of the hetero multimers. Kvf31.2 accelerates the rate of inactivation of the Shaker currents, as previously described, increases significantly the amplitude of the endogenous currents, and confers sensitivity to redo x modulation and hypoxia to Kv4.2 chann els. Upon association with Kvf31.2, Kv4.2 can be modi- fied by DTT (1,4 dithiothreitol) and DTDP (2,2'-dithiodipyridine), which also modulate the low pO2 response of the Kv4.2+f3 chann els. However, the physiological redu cing agent GSH ( redu ced glutathione) did not mimic the effects of DTT. Finally, hypoxic inhibition of Kv4.2+f3 currents can be reverte d by 70% in the presence of carbo n monoxide and remains in cell-free patches, suggesting the presence of a hemoproteic O2 sensor in HEK293 cells and a membrane-delimited mechanism at the origin of hypoxic responses. We conclude that f3 subunits can mod- ulate differe nt properties upon association with differe nt KV chann el subfamilies; of potential relevance to under- standing the molecular basis of low pO2 sensitivity in native tissues is the here described acquisition of the ability of Kv4.2+f3 chann els to respond to hypoxia.
Palabras Clave: Canales de potasio
Hypoxia
ISSN: 0022-1295
Revisión por Pares: SI
Propietario de los Derechos: Rockefeller University Press
Idioma: eng
URI: http://uvadoc.uva.es/handle/10324/25919
Derechos: info:eu-repo/semantics/openAccess
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