Promoter analysis of the human translation termination factor 1 gene

The human translation termination factor 1 (ETF1) gene encodes a class-1 release factor, eRF1, which catalyses termination of protein synthesis at all three stop codons. In this report, we describe the functional organization of the 5'-region of the gene. Primer extension and ribonuclease protection mapping revealed three transcription start sites clustered within approximately 10 bp. DNase I-hypersensitive site analysis identified five hypersensitive sites, one of which was located downstream of the initiation start sites. We used transient expression assays to define the 5'-regulating regions and in vivo and in vitro footprinting analysis to identify potential cis-acting regulatory elements. A basal promoter, spanning nucleotides -210/+117, contained no TATA box but a putative initiator element (Inr) and multiple potential Sp1/Sp3 binding sites, and thus displayed some of the features of a housekeeping gene. An additional upstream promoter containing positive and negative regulatory elements also regulated ETF1 gene expression. Real-time quantitative RT-PCR analysis showed tissue-specific expression of ETF1 transcripts in mouse tissues. Our results are suggestive of a constitutive expression of the human ETF1 gene but with possible cell- and tissue-specific regulation.