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). These proteins can be parts of the yeast (eukaryotic) Vacuolar (Acidocalcisome) Polyphosphate Polymerase (V-PPP) Family (TC# 4.E.1).
This family belongs to the Polyphosphate Polymerase/YidH (PoPo) Superfamily.
References:
Eichmann, C., J. Orts, C. Tzitzilonis, B. Vögeli, S. Smrt, J. Lorieau, and R. Riek. (2014). Intermolecular detergent-membrane protein noes for the characterization of the dynamics of membrane protein-detergent complexes. J Phys Chem B 118: 14288-14301.
Gerasimaitė, R., S. Sharma, Y. Desfougères, A. Schmidt, and A. Mayer. (2014). Coupled synthesis and translocation restrains polyphosphate to acidocalcisome-like vacuoles and prevents its toxicity. J Cell Sci 127: 5093-5104.
Müller, O., H. Neumann, M.J. Bayer, and A. Mayer. (2003). Role of the Vtc proteins in V-ATPase stability and membrane trafficking. J Cell Sci 116: 1107-1115.
Examples:
TC#	Name	Organismal Type	Example
9.B.51.1.1	Membrane DUF202 protein of 115 aas and 3 TMSs, YidH. YidH exhibits large tertiary structural fluctuations such as an opening between helices or the presence of large rotational dynamics of the helices (Eichmann et al. 2014).		YidH of E. coli

9.B.51.1.2	Uncharacterized DUF202 protein of 120 aas and 3 TMSs		DUF202 protein of Bacillus firmus

9.B.51.1.3	Uncharacterized protein of 109 aas and 3 TMSs.		UP of Waddlia chondrophila

9.B.51.1.4	pf02656 domain containing protein with 351 aas and 3 C-terminal TMSs.		pf02656 domain protein of Colletotrichum orbiculare

9.B.51.1.5	Uncharacterized protein of 149 aas and 3 TMSs.		UP of Scheffersomyces stipitis (Pichia stipitis)

9.B.51.1.6	VTC1 or PHM4 protein of 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 sectors, VTCs are important factors in vacuolar membrane fusion (Müller et al. 2003).	Fungi	VTC1 of Saccharomyces cerevisiae

9.B.51.1.7	DUF202 protein of 115 aas and 3 TMSs		DUF202 protein of Rhodococcus opacus

9.B.51.1.8	Vacuolar transport chaperone-like protein, Vtc1, of 158 aas and 3 TMSs.		Vtc1 of Chlamydomonas reinhardtii (Chlamydomonas smithii)

9.B.51.1.9	Uncharacterized protein of 128 aas and 3 TMSs.		UP of Chlamydomonas reinhardtii (Chlamydomonas smithii)