Isolation and characterization of the human gene encoding I-to: further diversity by alternative mRNA splicing

The transient outward K+ current (I-to) in the heart is responsible for the initial phase of repolarization and for setting the plateau voltage of the ventricular action potential. Recently, Kv4.3 has emerged as the leading c andidate alpha-subunit gene that underlies I-to in larger mammals such as d ogs and humans. we have cloned the human Kv4.3 homolog and describe a carbo xyl-terminal splice variant that inserts 19 amino acids with a consensus pr otein kinase C (PKC) phosphorylation site into the protein after the last m embrane-spanning segment. The coding region of Kv4.3 is comprised of at lea st five exons and is located on chromosome 1p13.3. In the basal state the b asic biophysical properties of bath of the splice variants are identical.