Isolation and Characterization of a Calcium Channel Gene, Cacna1f, the Murine Orthologue of the Gene for Incomplete X-Linked Congenital Stationary Night Blindness

Abstract

The mutant L-type calcium channel α1-subunit gene, CACNA1F, was recently identified as the gene responsible for incomplete X-linked congenital stationary night blindness. The 6070-bp mRNA transcript is predicted to encode a 1977-amino-acid pore-forming protein with cytoplasmic amino- and carboxyl-termini separated by four homologous repeat domains, each consisting of six transmembrane segments. CACNA1F has been shown to be preferentially expressed in the retina, indicative of a specific functional role in visual processing. We have established the complete sequence of the murine orthologue of CACNA1F, namely Cacna1f. The total length of the mRNA transcript of the murine gene was established to be 6080 bp with an open reading frame that translates into a 1985-amino-acid protein. Cacna1f is highly homologous to the human sequence, with 90% identity at the amino acid level and almost perfect conservation between the functional domains. Furthermore, as in the human gene, the 3′ end of the Cacna1f gene maps within 5 kb of the 5′ end of the mouse synaptophysin gene in a region orthologous to Xp11.23. Using in situ hybridization, Cacna1f was found to be expressed in the inner and outer nuclear layers and the ganglion cell layer of the retina.