Molecular characterization of the gene encoding the gamma subunit of the human skeletal muscle 1,4-dihydropyridine-sensitive Ca2+ channel (CACNLG), cDNA sequence, gene structure, and chromosomal location.

cDNA clones of the gamma subunit of the skeletal muscle 1,4-dihydropyridine-sensitive voltage-dependent Ca2+ channel were isolated from a human fetal skeletal muscle cDNA library using the rabbit gamma cDNA as a probe. The DNA sequence of the entire human cDNA was determined. Cosmids that contained the human gamma gene were isolated and used to determine the genomic organization of the coding sequences. Four exons were identified, spanning 12.5 kilobases of DNA. Reverse-transcribed polymerase chain reaction analysis detected the gamma transcript in human and mouse skeletal muscle RNAs, but not in RNA from human brain or cardiac muscle or from mouse brain, cardiac muscle, spleen, kidney, liver, or stomach. A polymorphic dinucleotide repeat within the gamma gene was identified. This repeat was used to type a subset of the Centre d'Etude du Polymorphisme Humain families. Linkage analysis indicates that the gamma gene is tightly linked (Z = 12.94, theta = 0.001) to growth hormone at chromosome 17q23, a region that also contains the adult skeletal muscle Na+ channel.