Distal element(s) is(are) required for position-independent expression of the goat alpha-lactalbumin gene in transgenic mice. Potential relationship with the location of the cyclin T1 locus

We recently reported the site-independent and copy-number-related expressio n in mice of a goat alpha -lactalbumin gene with 150 kb and 10 kb of 5'- an d 3'-flanking sequences, respectively. In the present study, we observed th at the resection of the 5'-flanking region, leaving only 70 kb, resulted in a site-dependent expression of this milk protein-encoding transgene. This suggests that important cis-regulatory elements are located within the dist al-deleted sequence. Within this region, we localised the promoter of the c yclin T1 gene, an ubiquitously expressed gene. So far, no other gene has be en located between these two loci. Since these two genes are differentially expressed, our data suggest that potential location of an insulator within the deleted region that allows that two genes to be independently regulate d.