Although these proteins, which are known collectively as group IV decarboxylases [PMID:8181483], probably share a common evolutionary origin, their levels of sequence similarity are low, being confined to a few short conserved regions. The tomato ADC gene contains an open reading frame encoding a polypeptide of 502 amino acids and a predicted molecular mass of ~55 kD [PMID:8022938]. The predicted amino acid sequence shares 47 and 38% identify with oat and Escherichia coli ADCs, respectively. Gel blot hybridisation experiments show that, in tomato, ADC is encoded by a single gene and is expressed as a transcript of ~2.2 kb in the fruit pericarp and leaf tissues [PMID:8022938].