A specific pattern of splicing for the horse $\alpha$S1-Casein mRNA and partial genomic characterization of the relevant locus

Dragan Milenkovic , Patrice Martin , Gérard Guérin , Christine Leroux

Mares' milk has a composition very different from that of cows' milk. It is much more similar to human milk, in particular in its casein fraction. This study reports on the sequence of a 994 bp amplified fragment corresponding to a horse $\alpha$S1-Casein ($\alpha$ S1-Cn) cDNA and its comparison with its caprine, pig, rabbit and human counterparts. The alignment of these sequences revealed a specific pattern of splicing for this horse primary transcript. As in humans, exons 3$'$, 6$'$ and 13$'$ are present whereas exons 5, 13 and 14 are absent in this equine mRNA sequence. BAC clones, screened from a horse BAC library, containing the $\alpha$ S1-Cn gene allowed the mapping of its locus by FISH on equine chromosome 3q22.2-q22.3 which is in agreement with the Zoo-FISH results. Genomic analysis of the $\alpha$ S1-Cn gene showed that the region from the second exon to the last exon is scattered within a nucleotide stretch nearly 15-kb in length which is quite similar in size to its ruminant and rabbit counterparts. The region between $\alpha$ S1- and $\beta$-Cn genes, suspected to contain cis-acting elements involved in the expression of all clustered casein genes, is similar in size (ca 15-kb) to the caprine and mouse intergenic region.

Mots clés: horse; $\alpha$S1-Casein; cDNA; localisation

Domaines: Génétique animale

Dragan Milenkovic, Patrice Martin, Gérard Guérin, Christine Leroux. A specific pattern of splicing for the horse $\alpha$S1-Casein mRNA and partial genomic characterization of the relevant locus. Genetics Selection Evolution, 2002, 34 (4), pp.509-519. ⟨10.1051/gse:2002020⟩. ⟨hal-00894424⟩