RESUMO
The ubiquitously expressed rat BAF60b gene, which codes for a subunit of the multiprotein SWI/SNF complex, was recently identified between the pituitary growth hormone (GH-N) and thyroid hormone receptor interacting protein-1 (TRIP-1) genes. In primates, duplication of the GH-N gene has resulted in the addition of four placenta-specific (GH-V, CS-A, CS-B, and CS-L) genes downstream of the GH-N gene. As part of our study of the effect of remote sequences on the transcriptional regulation of the GH/CS gene family, we showed recently that these genes lie 40 kb upstream of the human TRIP-1 gene. We have now investigated the presence of the human BAF60b gene upstream of the TRIP-1 gene for evidence of evolutionary conservation of this arrangement or its disruption by the recent duplication of the nearby GH-N gene in primates. We report that, as in the rat genome, the human BAF60b gene is in the reverse transcriptional direction relative to the TRIP-1 gene, such that their polyadenylation sites are separated by 93 bp which compares with 92 bp in the rat. Reexamination of reported porcine TRIP-1 sequences also revealed the presence of the BAF60b gene separated by 93 bp, supporting an evolutionary conservation of this arrangement.
