Abstract: Activation(depolarization) and recovery(repolarization) of the heart is the result of the orchestrated activity of a variety of ion channels and transporters. Potassium currents such as the transient outward potassium current, I_to, contribute significantly to phase 1 of repolarization. hKv4.3 is the predominant gene that is believed to underlie I_to in the human ventricle. The regulation of hKv4.3 at the transcriptional level was examined by cloning its promoter region and associated negative regulatory elements. Serial deletions of the 5' flanking region identified the minimal promoter of hKv4.3 at-156 to +2 bp surrounding the transcriptional start site. The promoter is not cell type specific and lacks a canonical TATA box. Three motifs found within the promoter include an E-box(CANNTG), a CArG-box[CC(A/T)₆GG], and a CACC-box. The CArG-box is necessary for transcriptional activity. A novel repressor element named T was identified. The deletion of the T element will at least double promoter activity.

Key words: hKv4.3, Minimal promoter, Repressor