9.B.51 The Uncharacterized DUF202/YidH (YidH) Family
Members of the YidH Family include YidH of E. coli which has 115 aas and 3 TMSs, the first TMS having a low level of hydrophobicity, the second, having a moderate level of hydrophobicity, and the third, having very hydrophobic character. These traits appear to be characteristic of most members of this family. The transmembrane α-helical nature of YidH has been established (Eichmann et al. 2014). Members of this family are found in bacteria, archaea and eukaryotes. In fungi, long homologues of ~ 350 aas have the 3 TMS DUF202 domain at its extreme C-terminus, and it has a pf02656 domain.
VTC1 or PHM4 protein of Saccharomyces cerevisiae (9.B.51.1.6) has 129 aas and 3 TMSs. This protein corresponds to the C-terminal domain of polyphosphate polymerase (TC# 4..E.1) (Gerasimaitė et al. 2014). VTC proteins influence the vacuolar H+-ATPase (V-ATPase) as well as vacuolar H+ uptake. Like the V-ATPase V0 sector, VTCs are important factors in vacuolar membrane fusion (Müller et al. 2003).