Transaldolase (EC 2.2.1.2) catalyzes the reversible transfer of a three-carbon ketol unit from sedoheptulose 7-phosphate to glyceraldehyde 3-phosphate to form erythrose 4-phosphate and fructose 6-phosphate. This enzyme, together with transketolase, provides a link between the glycolytic and pentose-phosphate pathways. Transaldolase is an enzyme of about 34 Kd whose sequence has been well conserved throughout evolution. A lysine has been implicated [1] in the catalytic mechanism of the enzyme; it acts as a nucleophilic group that attacks the carbonyl group of fructose-6-phosphate.

Transaldolase is evolutionary related [2] to a bacterial protein of about 20 Kd (known as talC in Escherichia coli), whose exact function is not yet known.

We developed two signature patterns for these proteins. The first, located in the N-terminal section, contains a perfectly conserved pentapeptide; the second, includes the active site lysine.