5'-RACE and genomic cloning were used to determine that the mouse TBP (mTBP) gene consists of one 5'-terminal non-coding exon followed by seven protein-coding exons. The region upstream of the first exon lacks a TATA-box. Hence, as with the case of other genes carrying TATA-less promoter, transcription starts from a cluster of sites which are located at the restricted region of mTBP gene. Interestingly, sequences of this region are well conserved between human and mouse TBP genes, suggesting that both mouse and human TBP genes drive mRNA synthesis in a similar way, and the sequence homology between two genes was used to assign a putative start point for the human TBP gene. Mouse, human, and Trimersurus gramineus (green habu snake) TBP genes share two GC-rich regions in their promoter regions. Thus, it is probable that diverse species of vertebrates commonly use TATA-less promoter bearing GC-rich regions to direct ubiquitous TBP expression.