A strong promoter element is located between alternative exons of a gene encoding the human gamma-aminobutyric acid-type A receptor beta 3 subunit (GABRB3).
The gene that encodes the beta 3 subunit of the gamma-aminobutyrate-Type A (GABAA) receptor is widely expressed in brain tissue and has been associated with imprinted genetic disorders. Here, the 5' regions of the human and rat genes were characterized and found to be highly conserved in both coding and non-coding sequences. A novel transcript of the human gene revealed the existence of an alternative exon 1 (exon 1a) that encodes a variant signal sequence. Relative levels of the alternative transcripts were found to vary between fetal and adult brain, and between different brain regions. Endogenous beta 3 subunit transcripts were also detected in several immortalized cell lines, including human kidney 293 cells. Transcription of exon 1 is initiated from multiple sites within a pyrimidine-rich region of the gene. This region of the human gene also exhibits strong promoter activity and binds nuclear factors at a site which overlaps the transcriptional start sites. The promoter element was shown to bind Sp1 and at least one other unidentified nuclear factor.
Section on Molecular Neurobiology, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, Maryland 20852.
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Kirkness
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Fraser
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D004247:DNA; D005091:Exons; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D051381:Rats; D011963:Receptors, GABA-A / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D011963:Receptors, GABA-A; D004247:DNA; D015500:Chloramphenicol O-Acetyltransferase