Jm. Folch et al., Differential expression of bovine beta-lactoglobulin A and B promoter variants in transiently transfected HC11 cells, J DAIRY RES, 66(4), 1999, pp. 537-544
Quantification of beta-lactoglobulin A and B in the milk of heterozygous an
imals has revealed a differential content of these two variants. Nucleotide
sequence analysis of the first 733 bp of the bovine beta-lactoglobulin pro
moter has indicated the presence of ten polymorphic sites, nine of them bei
ng allele A and B specific mutations. To study the differential expression
of these alleles, constructs containing 753 bp long fragments of the bovine
beta-lactoglobulin A and B associated promoters mere used in transient tra
nsfection experiments in HC11 cells. A differential transcription activity
directed by the A and B specific promoters was consistently observed. The r
elative expression levels were 57% for beta-lactoglobulin A and 43% for bet
a-lactoglobulin B promoters. An allele-specific mutation has been reported
to have a differential binding affinity to the activator protein-2 between
the beta-lactoglobulin A and B promoters. However, experiments in HC11 cell
s where the activator protein-2 binding sites were mutated in both beta-lac
toglobulin A and B promoters showed no major differences in activity betwee
n the mutated and native promoters.