GTBP is one of the functional homologues of the bacterial mismatch repair gene mutS, whose product forms a heterodimer with hMSH2 to bind to the mismatched region of double-stranded DNA. We determined the expression of the GTBP gene and found that two forms of the transcripts were ubiquitously expressed in normal human tissues. These transcripts, termed GTBP-N and GTBP-ALT, were generated by the alternative splicing machinery. These two transcripts share 3172 bp from the translation initiation codon that codes for 1057 amino acids. GTBP-ALT lacked a region that codes for a highly conserved region between GTBP-N, hMSH2, and hMSH3 in their C-termini.