PROMOTER AND TRANSCRIPTION START SITE OF HUMAN AND RABBIT BUTYRYLCHOLINESTERASE GENES

Two kilobase segments of the 5'-untranslated regions of the human and rabbit butyrylcholinesterase (BCHE) genes were characterized. The sequ ences shared extensive identity except for a 333-base pair (bp) Alu re peat present only in human BCHE. One single transcription start site w as found in both genes with the techniques of primer extension, amplif ication of the 5'-end of mRNA, and RNase protection. Cap sites in huma n and rabbit BCHE genes were found in strictly homologous positions. I n human BCHE, the transcription start site was found 157 bp upstream o f Met(-28), the translation start site. Potential regulatory elements in both promoters included one AP1 site and multiple sites for topoiso merase, Oct-1 and PEA-3. Transient expression of BCHE-reporter gene co nstructs showed that a 194-bp fragment of the 5'-flanking region of hu man BCHE and a 570-bp fragment of rabbit BCHE were sufficient for prom oting chloramphenicol acetyltransferase activity in HeLa cells. No con sensus TATA and CAAT boxes were found. However, the sequence around th e transcription start site exhibited homology with initiator elements found in other TATA-less promoters in developmentally regulated genes.