Gene structure of rat BAF60b, a component of mammalian SW1/SNF complexes, and its physical linkage to the growth hormone gene and transcription factor SUG/proteasome p45 gene.

In the +27.6 to +36.7 kb downstream region from the transcriptional start site of the rat growth hormone (GH) gene, a gene encoding BAF60b, a component of mammalian SWI/SNF complexes, was found to have the same transcriptional orientation as the GH gene. The 5' end of the BAF60b gene was heterogeneous and the longest gene was 9060 bp long with 13 exons. The largest of all exons was estimated to be 2774 bases. Deduced rat BAF60b protein was made of 531 amino acids and its amino acid sequence was 97% identical with the human counterpart. No TATA box was found up to the -100 bp region but five GC boxes corresponding to the Sp1 binding site were observed up to 640 bp upstream from the transcriptional start site. Sixty-three bases downstream from the BAF60b gene, the polyadenylation site of the gene encoding transcription factor SUG/proteasome p45, whose expression is constant in many tissues, was identified. The BAF60b gene was expressed as 3.0 kb poly(A)-rich RNA in seven tissues and one cell line from rat but its expression varied considerably according to the tissue.