Kir family isoform profiling strategy. 1) Alignment of Kir channel isoform nucleic acid sequences revealed regions of high sequence similarity. Two conserved motifs, G(Y/F)G and ILE, in the pore and C terminal domains respectively, were selected and Kir isoforms cloned. 2) Poly A+ RNA was isolated from a single cell type and 3) degenerate (dg) PCR performed with sub-family centred primers. Degenerate PCR products were radio end-labelled, recovered free of unincorporated nucleotides and cleaved with frequent-cutting restriction enzyme (ScrF I) and resolved by agarose gel electrophoresis.