Molecular cloning and characterization of alpha lactalbumin gene of Vechur cattle

A 1756 bp fragment of the alpha-lactalbumin (alpha-LA) gene of Vechur cattle covering the entire transcriptional unit was PCR-amplified from genomic DNA and was sequenced by the dideoxynucleotide method after cloning in a T-vector. The Vechur alpha-LA gene has an open reading frame of 426 nucleotides encoding a signal peptide of 19 amino acid residues and a mature protein of 123 amino acid residues with NH(2-)terminal glutamic acid and COOH- terminal leucine (Accession # EU 200932). Sequence analysis showed that 122 amino acid residues are identical with that of Bos taurus alpha-LA and 73% identity was observed with human alpha-LA protein. The nucleotide sequence of Vechur cattle alpha-LA gene was having 99% homology with that of Bos taurus, 98% with that of yak and 95% with that of sheep alpha-LA gene. The exon-intron boundaries are conserved in Vechur and Bos taurus as well as in human. This strict homology in the sites of insertion of introns suggests that the exon-intron organization of these genes was established before the divergence of these species. The positions of the exon-intron boundaries are also conserved as evidenced from similar sizes of the exons. The degree of structural or functional similarity between Vechur and human alpha-LA proteins was almost similar to the similarity between Bos taurus and human alpha-LA proteins.