Transketolase (TKT;) is a thiamine-dependent enzyme that links the pentose phosphate pathway with the glycolytic pathway. As part of a systematic search for differentially expressed genes, Coy et al. (1996) isolated a novel transketolase-related gene, TKTL1, which they called TKR. They isolated transcripts encoding tissue-specific protein isoforms. Comparison with known transketolases demonstrated a TKR-specific deletion mutating 1 thiamine-binding site.

Genomic sequencing of the TKR gene by Coy et al. (1996) revealed the presence of a pseudoexon, as well as the acquisition of a tissue-specific spliced exon, compared to the TKT gene, which maps to 3p14.3.