Partial structure, chromosome localization, and expression of the mouse Girk4 gene.

The G protein-gated potassium channel IKACh constitutes part of a signaling pathway that mediates the negative chronotropic and inotropic effects of acetylcholine on cardiac physiology. Similar or identical ion channels regulate the excitability of many neurons in response to neurotransmitters. IKACh is composed of two homologous subunits, GIRK1 and GIRK4. Here we describe a partial genomic structure of the mouse Girk4 gene. Two exons containing the complete protein-coding sequence were identified. Girk4 was mapped to mouse chromosome 9 (13 cM), consistent with the mapping of human GIRK4 to chromosome 11q23-ter. GIRK4 mRNA was found mainly in mouse heart, with trace levels detected in brain, kidney, lung, and spleen. No detectable levels were observed in skeletal muscle, liver, and testis. The onset of GIRK4 mRNA expression in the developing mouse occurs between Embryonic Days 7 and 11, consistent with the appearance and function of the mouse heart.