Galactose-1-Phosphate Uridylyltransferase (GALT)

Galactose-1-phosphate uridyl transferase (GALT) catalyzes the second step of the Leloir pathway of galactose metabolism, namely the conversion of UDP-glucose + galactose-1-phosphate to glucose-1-phosphate + UDP-galactose. The absence of this enzyme results in classic galactosemia in humans and can be fatal in the newborn period if lactose is not removed from the diet. The pathophysiology of galactosemia has not been clearly defined.This 16-kb transcription unit contains 2 promoters (the first one constitutive, and the second, 8 kb downstream, highly regulated) and 2 cleavage/polyadenylation signals separated by 12 kb. The promoter from the GALT gene yields 2 mRNAs, a 1.4-kb mRNA encoding GALT and a 3-kb fusion mRNA when the first poly(A) site is spliced out and the second poly(A) site is used.