Binding Site

Transketolase binding site (IPR020826)

Short name: Transketolase_BS


Transketolase EC: (TK) catalyzes the reversible transfer of a two-carbon ketol unit from xylulose 5-phosphate to an aldose receptor, such as ribose 5-phosphate, to form sedoheptulose 7-phosphate and glyceraldehyde 3- phosphate. This enzyme, together with transaldolase, provides a link between the glycolytic and pentose-phosphate pathways. TK requires thiamine pyrophosphate as a cofactor. In most sources where TK has been purified, it is a homodimer of approximately 70 Kd subunits. TK sequences from a variety of eukaryotic and prokaryotic sources [PMID: 1567394, PMID: 1737042] show that the enzyme has been evolutionarily conserved. In the peroxisomes of methylotrophic yeast Pichia angusta (Yeast) (Hansenula polymorpha), there is a highly related enzyme, dihydroxy-acetone synthase (DHAS) EC: (also known as formaldehyde transketolase), which exhibits a very unusual specificity by including formaldehyde amongst its substrates.

1-deoxyxylulose-5-phosphate synthase (DXP synthase) [PMID: 9371765] is an enzyme so far found in bacteria (gene dxs) and plants (gene CLA1) which catalyzes the thiamine pyrophosphoate-dependent acyloin condensation reaction between carbon atoms 2 and 3 of pyruvate and glyceraldehyde 3-phosphate to yield 1-deoxy-D- xylulose-5-phosphate (dxp), a precursor in the biosynthetic pathway to isoprenoids, thiamine (vitamin B1), and pyridoxol (vitamin B6). DXP synthase is evolutionary related to TK. The N-terminal section, contains a histidine residue which appears to function in proton transfer during catalysis [PMID: 1628611]. In the central section there are conserved acidic residues that are part of the active cleft and may participate in substrate-binding [PMID: 1628611]. This family includes transketolase enzymes EC: and also partially matches to 2-oxoisovalerate dehydrogenase beta subunit P37941 EC: Both these enzymes utilise thiamine pyrophosphate as a cofactor, suggesting there may be common aspects in their mechanism of catalysis.

This entry is located in the central section and contains conserved acidic residues that are part of the active cleft and may participate in substrate-binding [PMID: 1628611].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns