FUNCTIONAL EXPRESSION AND CELLULAR MESSENGER-RNA LOCALIZATION OF A G-PROTEIN-ACTIVATED K-BRAIN( INWARD RECTIFIER ISOLATED FROM RAT)

We have cloned by homology screening from a rat brain cDNA library a G IRK3-type (Kir 3.3) inwardly rectifying K+ channel subunit with high s tructural similarity to other subfamily members whose activity is thou ght to be controlled by receptor-stimulated G proteins. when heterolog ously expressed both in Xenopus oocytes and in mammalian COS-7 cells, rbGIRK3 subunits individually fail to form functional channels. In con trast, when coexpressed with other GIRK subunits, rbGIRK3 gives rise t o prominent currents which are enhanced by the stimulation of coexpres sed 5-HT1A receptors. In-situ hybridizations show that of all GIRK sub units rbGIRK3 is most widely distributed and strongly expressed throug hout the rat brain and thus may play an important role in central sign al processing. (C) 1996 Academic Press, Inc.