Potassium Inwardly Rectifying Channel Subfamily J, Member 3 (KCNJ3)

Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. KCNJ3 is an integral membrane protein and inward-rectifier type potassium channel. The encoded protein, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, is controlled by G-proteins and plays an important role in regulating heartbeat. It associates with three other G-protein-activated potassium channels to form a hetero-tetrameric pore-forming complex.The cDNA encodes a predicted 501-amino acid protein whose sequence is 99% identical to that of rat GIRK1. Northern blot analysis showed that human GIRK1 is expressed as 2 mRNAs (4.3 kb and 6.2 kb) that are most abundant in brain, but are also seen in kidney and heart.