4.D.2 The Glycosyl Transferase 2 (GT2) Family

The GT2 (COG0392) family has been implicated in several distinct functions including drug resistance and various enzymatic activities. Most members have about 8 - 10 TMSs plus a ~340aa C-terminal hydrophilic domain that may have catalytic activity. These proteins are implicated in glycosyl transfer with concomitant export across the membrane. They show very significant similarity to extra N-terminal domains in 3.A.3.4.3 and 4.  These two putative Mg²⁺ P-type ATPases (but not others in this subfamily) have N-terminal duplications probably of 6 + 4 TMSs, and this duplicated region is shared by membres of this family (the GT2 family) as well as 4.H.1 (The Lysyl Phosphatidylglycerol Synthase/Flippase (MprF) Family).  In all three families, this region may function to flip the substrate from the inner surface of the membrane to the out surface of it.  The C-terminal domain in TC family 4.H.1 is related to the MFS (Wang et al. 2020).