Structure of Artemia franciscana sarco/endoplasmic reticulum Ca-ATPase gene.

Genomic clones coding for the Artemia franciscana sarco(endo)plasmic reticulum Ca-ATPase have been isolated. The restriction map of the overlapping clones covers a region of 65 kilobases of DNA. Nucleotide sequence of mRNA coding regions shows that the gene is divided into 18 exons separated by 17 introns. Compared with the structure of the rabbit sarco(endo)plasmic reticulum Ca-ATPase 1 gene, 12 of the introns are in the same position, 8 introns present in the rabbit gene are absent from A. franciscana, 4 introns present in A. franciscana are not found in rabbit, and the position of 1 intron is shifted one base between both genes. Southern blot analysis strongly suggests that this is the only sarco(endo)plasmic reticulum Ca-ATPase gene present in A. franciscana. Primer extension and nuclease S1 protection experiments have shown the existence of two main regions of transcription initiation separated by 30 nucleotides. Transcription is initiated in both regions at two or three consecutive bases. A hexanucleotide that includes the initiation sites is repeated in both transcription initiation regions. The nucleotide sequence of the promoter region shows the existence of several putative regulatory sites, including some that are muscle-specific such as one CArG box, 3 MEF-2, and 8 putative binding sites for muscle transcription factors of the MyoD family.