Complete nucleotide sequence, structural organization, and an alternatively spliced exon of mouse h1-calponin gene.

From a CC1.2 embryonic stem cell genomic library, we isolated and sequenced a 10.4-kb DNA segment (GenBank/EMBL Data Bank accession number L49022) containing the entire gene encoding mouse h1-calponin, an actin-associated smooth muscle-specific protein and a potential modulator of contraction. Sequence data revealed that there are seven exons and six introns in the h1-calponin gene. Determined by primer extension mapping of the RNA transcripts, the transcription of h1-calponin gene initiates at the same site in stomach, urinary bladder and pregnant uterus smooth muscles. The genomic organization suggests that the previously identified alpha- and beta-calponin isoforms are produced by splicing of exon 7 at two alternative acceptor sites. Isolation and structural characterization of the h1-calponin gene provides information to further investigate the expression regulation of this smooth muscle-specific gene.