Journal of Dairy Research

A single nucleotide polymorphism in the bovine β-casein promoter region across different bovine breeds 1

Aileen F Keating a1, Terry J Smith a2, Paul Ross a3 and Michael T Cairns a1c1
a1 National Diagnostics Centre, National University of Ireland, Galway, Ireland
a2 National Centre for Biomedical Engineering Science, National University of Ireland, Galway
a3 Teagasc, Dairy Products Research Centre, Moorepark, Fermoy, Co. Cork, Ireland

Article author query
keating af   [PubMed][Google Scholar] 
smith tj   [PubMed][Google Scholar] 
paul ross r   [PubMed][Google Scholar] 
cairns mt   [PubMed][Google Scholar] 

The bovine β-casein (CSN2) gene has been shown to span a region of 8·5 kb, containing nine exons and eight intervening introns (Bonsing et al. 1988; Martin et al. 2002). The exons range in size from 24 to 498 bp; the introns, however, are much larger and account for 85% of the gene. Twelve genetic variants in the coding sequence of the β-casein gene have been reported (Farrell et al. 2004). The A2 allele of the β-casein gene has been associated with a higher milk production (Lin et al. 1986; Bech & Kristiansen, 1990) while the B variant has been associated with an increase in protein content and better cheesemaking properties (Marziali & Ng-Hang-Kwai, 1986). The β-casein gene codes for a protein of 209 amino acids with varying regions at codons 67, 106 and 122. The A1 variant differs from A2 at position 67, where a histidine replaces a proline (Lien et al. 1992). The β-casein A2 variant has histidine and the A3 variant has glycine at position 106 (Lien et al. 1992); the β-casein A2 variant has serine at position 122 and the β-casein B variant has arginine at this codon (Stewart et al. 1987; Damiani et al. 1992).

(Published Online February 14 2006)
(Received June 27 2005)
(Accepted September 5 2005)

Key Words: β-casein; SNP; bovine.

c1 e-mail:


1 The nucleotide sequence data reported in this paper have been submitted to GenBank and have been assigned the accession number AJ973327