The goat as1-casein gene: gene structure and promoter analysis

The level of αs1-casein in goat milk shows strong variations determined by at least 15 alleles associated with four different efficiencies of protein synthesis. The nucleotide sequence of the whole goat αs1-casein-encoding gene (CSN1S1) plus 1973 nucleotides at the 5′ flanking region and 610 nucleotides at the 3′ flanking region was determined and aligned with its bovine counterpart. The gene is spread over 16.7 kb and consists of 19 exons varying in length from 24 bp (exons 5, 6, 7, 8, 10, 13 and 16) to 385 bp (exon 19) and 18 introns from 90 bp of intron 10 to 1685 bp of intron 2. Furthermore, highly conserved sequences, mainly located in the 5′ flanking region, were found between this gene and other casein-encoding genes. Finally, seven interspersed repeated elements (10 in the bovine CSN1S1 gene) were also identified at four different locations of the sequenced region: 5′ untranscribed region and introns 2, 8 and 11.