Molecular cloning and phylogenetic analysis of canine β-casein

A canine beta -casein cDNA was isolated from mammary tissue by polymerase chain reaction (PCR) using degenerate primers. It encodes 250 amino acids protein containing the conserved sequence motif of beta -casein. It showed the highest homology with snow-leopard (Uncia uncia) (55-62 % identity). It also showed 44-53% identity with human, 33-42 % identity with mouse, 29-37% identity with rat, 43-53 % identity with rabbit, 41-48% identity with pig, 44-51% identity with cattle and 44-50 % identity with sheep. A 1.2-kb mRNA was detected in mammary tissue by Northern blot analysis. Phylogenetic analysis revealed that canine beta -casein formed a branch with lesser panda and snow leopard, which were grouped into carnivore.