This is the major methanol assimilatory enzyme from the methylotrophic Hansenula polymorpha. D-xylulose 5-phosphate + formaldehyde = D-glyceraldehyde 3-phosphate + dihydroxyacetone Binds 1 Mg(2+) ion per subunit. Can also utilize other divalent metal cations, such as Ca(2+), Mn(2+) and Co(2+). Binds 1 thiamine pyrophosphate per subunit. Belongs to the transketolase family.