G1P_TT_long represents the long form of glucose-1-phosphate thymidylyltransferase.
This family is the long form of Glucose-1-phosphate thymidylyltransferase. Glucose-1-phosphate thymidylyltransferase catalyses the formation of dTDP-glucose, from dTTP and glucose 1-phosphate. It is the first enzyme in the biosynthesis of dTDP-L-rhamnose, a cell wall constituent and a feedback inhibitor of the enzyme.There are two forms of Glucose-1-phosphate thymidylyltransferase in bacteria and archeae; short form and long form. The long form, which has an extra 50 amino acids c-terminal, is found in many species for which it serves as a sugar-activating enzyme for antibiotic biosynthesis and or other, unknown pathways, and in which dTDP-L-rhamnose is not necessarily produced.The long from enzymes also have a left-handed parallel helix domain at the c-terminus, whereas, th eshort form enzymes do not have this domain. The homotetrameric, feedback inhibited short form is found in numerous bacterial species that produce dTDP-L-rhamnose.