Abstract. The αS2-casein (αS2-CN) is a member of the casein
family associated with milk traits in ruminants, but so far the buffalo
CSN1S2 gene has not been well understood. In this work, the polymorphisms of
CSN1S2 in river and swamp buffalo were detected using direct sequencing of polymerase chain reaction (PCR) products. As a result, 13 single nucleotide polymorphisms (SNPs) were identified in the coding sequence (CDS) of CSN1S2 in two types
of buffalo, of which eight SNPs were non-synonymous. The amino acid changes
caused by c.580T>C and c.642C>G may affect the
function of buffalo αS2-CN. A total of 11 CSN1S2 CDS haplotypes were
defined, and accordingly 11 variants of buffalo αS2-CN were
inferred and named. The CSN1S2 CDSs of both types of buffalo were 669 nucleotides,
which encoded a precursor of 222 amino acids (AAs), and the first 15 AAs
constitute a signal peptide. The composition and physicochemical
characteristics of two types of buffalo αS2-CNs were similar
but slightly different from those of cattle αS2-CN. The
αS2-CN mature peptides of buffalo and the species of Bos genus contained a casein
domain, and their secondary structures were highly consistent, indicating
that they are functionally similar. The results here provide initial
insights into the variation, characteristics and biological function of
buffalo CSN1S2.