The cardiac Ca channel known as alpha(1C) or Ca(V)1.2 is shown to express a new longer first exon equivalent to that formerly reported in rabbit heart or rat aorta. Ribonuclease protection assay indicates that this exon is found in the majority of Ca(V)1.2 transcripts in human heart RNA. The presence of this exon also suggests that expression of this transcript is driven by a promoter immediately upstream of this exon and its 5' untranslated region. The putative promoter exhibits 69% homology to its rat counterpart and displays functional promoter activity when transfected into heart cells in culture in luciferase-expressing constructs. (C) 2002 Elsevier Science (USA). All rights reserved.