Molecular cloning and characterization of alpha lactalbumin gene of Vechur cattle

Abstract

A 1756 bp fragment of the alpha-lactalbumin (α-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 Tvector. The Vechur α-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 NH2-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 α-LA and 73% identity was observed with human α-LA protein. The nucleotide sequence of Vechur cattle α-LA gene was having 99% homology with that of Bos taurus, 98% with that of yak and 95% with that of sheep α-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 α-LA proteins was almost similar to the similarity between Bos taurus and human α-LA proteins.