inward rectifier potassium channel complex I(KACh) inward rectifier potassium channel complex GIRK1-GIRK4 G protein-coupled atrial inward rectifier potassium channel complex GO:1990566 An inward rectifier potassium channel complex expressed in cardiac muscle, specifically the sinoatrial node and atria, where it controls the heart rate, via regulation by G protein-coupled receptor signaling. In mammals it is composed of GIRK1 (or Kir3.1) and GIRK4 (or Kir3.4) subunits. ame 2014-11-26T15:16:14Z muscarinic potassium channel complex cellular_component Examples of this are KCNJ3 and KCNJ5 in human (Uniprot symbols P48549 and P48544) in PMID:9765280 inferred from orthology sequence evidence. Kir3.1-Kir3.4 G protein-coupled atrial inward rectifier potassium channel complex