Heteromultimeric Assembly of Human Potassium Channels

To gain insight into the molecular basis of cardiac repolarization, we have expressed K' channels cloned from ventricular myocardium in Xenopus oocytes. A recently identified human cardiac K' channel isoform (human Kvl.4) has properties similar to the 4-aminopyridine-sensitive calcium-insensitive component of the cardiac transient outward current. However, these channels recovered from inactivation much slower than native channels. Hybrid channels consisting of subunits from different K' channel clones (delayed rectifier channels [Kvl.l, Kv1.2, and Kvl.5] and Kvl.4) were created by coinjection of cRNAs in oocytes. Multimeric channels consisting of Kvl.4:Kvl.1, Kvl.4:Kvl.2, and Kvl.4:Kvl.5 were expressed and compared. The hybrid channels displayed characteristics of heterotetrameric channels with kinetics that