Polymorphisms of Bovine ß-Lactoglobulin Promoter and Differences in the Binding Affinity of Activator Protein-2 Transcription Factor

Lorraine S. Lum ¹, Peter Dov ¹, and Juan F. Medrano ¹

¹ Department of Animal Science, University of California, Davis 95616-8521

Differential production of the two most common allelic variants of ß-lactoglobulin (LG), ß-LG A and ß-LG B, has been observed using PAGE. This study evaluated 733 bp of the ß-LG promoter region and 92 bp of the first exon for possible polymorphisms using denaturing gradient gel electrophoresis and nucleotide sequence analysis. Within this region, 13 single nucleotide substitution polymorphisms were detected. Twelve polymorphisms were allele specific, and one appeared to be polymorphic only for the B allele. Several potential binding sites for transcription factors were found within the promoter sequence. This study investigated the role of the G to C transversion within a consensus binding site for activator protein-2 at position –430 bp upstream from the transcription initiation site. Using the DNase-I footprint assay, we confirmed the functional importance of this point mutation and showed different binding affinities of activator protein-2 for both alleles. We discuss the possible regulatory role of activator protein-2 in the transcriptional regulation of the ß-LG gene and propose the activator protein-2 transcription factor as a modulator of gene expression of ß-LG.

Key Words: activator protein-2 • ßbeta;-lactoglobulin • promoter • transcription factor

Submitted on March 25, 1996
Accepted on November 18, 1996

This article has been cited by other articles:

				M. H. Braunschweig Short Communication: Duplication in the 5'-Flanking Region of the {beta}-Lactoglobulin Gene is Linked to the BLG A Allele J Dairy Sci, December 1, 2007; 90(12): 5780 - 5783. [Abstract] [Full Text] [PDF]

				S. Chessa, F. Chiatti, G. Ceriotti, A. Caroli, C. Consolandi, G. Pagnacco, and B. Castiglioni Development of a Single Nucleotide Polymorphism Genotyping Microarray Platform for the Identification of Bovine Milk Protein Genetic Polymorphisms J Dairy Sci, January 1, 2007; 90(1): 451 - 464. [Abstract] [Full Text] [PDF]

				M. H. Braunschweig and T. Leeb Aberrant low expression level of bovine beta-lactoglobulin is associated with a C to A transversion in the BLG promoter region. J Dairy Sci, November 1, 2006; 89(11): 4414 - 4419. [Abstract] [Full Text] [PDF]

				A. W. Kuss, J. Gogol, H. Bartenschlager, and H. Geldermann Polymorphic AP-1 Binding Site in Bovine CSN1S1 Shows Quantitative Differences in Protein Binding Associated with Milk Protein Expression J Dairy Sci, June 1, 2005; 88(6): 2246 - 2252. [Abstract] [Full Text] [PDF]

				A. W. Kuss, J. Gogol, and H. Geldermann Associations of a Polymorphic AP-2 Binding Site in the 5'-Flanking Region of the Bovine {beta}-Lactoglobulin Gene with Milk Proteins J Dairy Sci, June 1, 2003; 86(6): 2213 - 2218. [Abstract] [Full Text] [PDF]