TCDB is operated by the Saier Lab Bioinformatics Group
TCIDNameDomainKingdom/PhylumProtein(s)
*2.A.9.1.1









Cytochrome oxidase biogenesis protein, Oxa1p (involved in the insertion of a wide range of membrane proteins).  Forms a cation-selective channel (4-state; diameter, 0.6 - 2.0 nm), regulated by the membrane potential and association with the substrate protein (Krüger et al. 2012).  The structure of the dimeric insertion pore associated with the translating ribosome has been solved (Kohler et al. 2009).

Eukaryota
Fungi
Oxa1p of Saccharomyces cerevisiae
*2.A.9.1.2









Mammalian Oxa1L has a C-terminal 100 aa tail that binds ribosomes and promotes translation coupled membrane insertion (Haque et al., 2010).

Eukaryota
Metazoa
Oxa1L of Homo sapiens (Q15070)
*2.A.9.1.3









Cytochrome c oxidase assembly protein 18, COX18 of 333 aas and 4 TMSs. Acts transiently as a membrane insertase within the subunit 2 module of Cytochrome oxidase (Bourens and Barrientos 2017). Plays a central role in the translocation and export of the C-terminal part of the COX2 protein into the mitochondrial intermembrane space (Gaisne and Bonnefoy 2006).

COX18 of Homo sapiens
*2.A.9.1.4









Cox18 (Oxa1-3; Oxa103) of 202 aas and 5 TMSs.  Required for the insertion of integral membrane proteins into the mitochondrial inner membrane (Gaisne and Bonnefoy 2006).

Cox18 of Schizosaccharomyces pombe (Fission yeast)
*2.A.9.2.1









Chloroplast protein, ALBINO3 (Alb3). Inserts a subset of light harvesting chlorophyll-binding proteins) (Gerdes et al., 2006). SRP43 (3.A.5.1.2) and the translocase, Alb3, interact directly (Dünschede et al., 2011). SRP43 is an ATP-independent chaperone containing ankyrin repeats required for the biogenesis of the most abundant class of membrane proteins, the light-harvesting chlorophyll a/b-binding proteins (LHCPs) (McAvoy et al. 2018).

Eukaryota
Viridiplantae
ALBINO3 of Arabidopsis thaliana
*2.A.9.2.2









Chloroplast protein ALBINO4 (Alb4) (essential for proper chloroplast biogenesis (Gerdes et al., 2006)
Eukaryota
Viridiplantae
ALBINO4 of Arabidopsis thaliana (CAJ45566)
*2.A.9.3.1









60 kDa inner membrane protein, YidC (involved in insertion of a wide range of membrane proteins, including anaerobic respiratory complexes (Price and Driessen, 2008). The thrid TMS in YidC contacts the substrate protein (Yu et al., 2008).  YidC occupies the lateral gate of the SecYEG translocase and is sequentially displaced by the nascent membrane protein (Sachelaru et al. 2013).  Residues involved in interaction with the Sec translocon have been identified (Li et al. 2014). YidC acts as a flexible chaperone, facilitating LacY folding (Zhu et al. 2013; Hennon and Dalbey 2014).  The structure of the dimeric insertion pore associated with the translating ribosome has been solved (Kohler et al. 2009).  A single copy of YidC interacts with the ribosome at the ribosomal tunnel; a site for membrane protein insertion at the YidC protein-lipid interface has been identified (Wickles et al. 2014).  The crystal structure of full-length E. coli YidC revealed that a hydrophilic groove, formed by five transmembrane helices, is a conserved structural feature as compared to the previous YidC structure from Bacillus halodurans, which lacks a periplasmic domain. Structural mapping of the substrate- or Sec protein-contact sites suggested the importance of the groove for the YidC functions as a chaperone and an insertase (Hennon and Dalbey 2014).  The structure of the dimeric insertion pore associated with the translating ribosome has been solved (Kohler et al. 2009).  A single copy of YidC interacts with the ribosome at the ribosomal tunnel; a site for membrane protein insertion at the YidC protein-lipid interface has been identified (Wickles et al. 2014).  The crystal structure of full-length E. coli YidC revealed that a hydrophilic groove, formed by five transmembrane helices, is a conserved structural feature as compared to the previous YidC structure from Bacillus halodurans, which lacks a periplasmic domain. Structural mapping of the substrate- or Sec protein-contact sites suggested the importance of the groove for the YidC functions as a chaperone and an insertase (Kumazaki et al. 2014).

Bacteria
Proteobacteria
YidC of E. coli
*2.A.9.3.2









Essential sporulation inner membrane protein, SpoIIIJ is a proposed membrane protein translocase that facilitates the insertion of SpoIIIAE into the membrane (Camp and Losik, 2008). Also facilitates membrane insertion of F-ATPase subunit c from B. subtilis and E. coli. Plays a role in membrane protein biogenesis rather than protein secretion (Saller et al., 2009).

Bacteria
Firmicutes
SpoIIIJ of Bacillus subtilis
*2.A.9.3.3









OxaA2 membrane protein biogenesis protein, OxaA2 or YqjG (Saller et al., 2009).

Bacteria
Firmicutes
OxaA2 of Bacillus subtilis (P54544)
*2.A.9.3.4









YidC homologue

Bacteria
Proteobacteria
YidC of Myxococcus xanthus
*2.A.9.3.5









YidC protein insertase.  The 3-D structure has been determined at 2.4 Å resolution (see the YidC Family discussion section).

Bacteria
Firmicutes
YidC1 of Bacillus halodurans
*2.A.9.3.6









YidC2.  The 3-D structure of YidC has been determined (Kumazaki et al. 2014).  The conserved positively charged residue within transmembrane segment one (at position 72) is located in a hydrophilic groove that is embedded in the inner leaflet of the lipid bilayer.  It is essential in Gram positive bacteria but not Gram negative bacteria or plant chloroplasts (Chen et al. 2014).

Bacteria
Firmicutes
YidC2 of Bacillus halodurans
*2.A.9.3.7









YidC of 562 aas and 4 - 6 TMSs. Shows sequence similarity to 1.A.106.2.4, TMSs 2 - 3 in both proteins.

YidC of Sutterella parvirubra
*2.A.9.3.8









Uncharacterized YidC homologue of 237 aas and 4 - 6 TMSs.

Bacteria
Candidatus Harrisonbacteria
YidC of Candidatus Harrisonbacteria bacterium
*2.A.9.3.9









Uncharacterized YidC homologue of 241 aas and 5 - 6 TMSs.

Bacteria
Candidatus Magasanikbacteria
YidC of Candidatus Magasanikbacteria bacterium
*2.A.9.4.1









Oxa2 (Cox18) YidC homologue (replace E. coli YidC for SecYEG-independent insertion by genetic complementation) (Bloois et al., 2007).
Eukaryota
Fungi
Oxa2 of Saccharomyces cerevisiae (P53239)
*2.A.9.5.1









Uncharacterized YidC homologue of 366 aas and 6 or 7 TMSs.

Bacteria
Candidatus Wirthbacteria
YidC of Candidatus Wirthbacteria bacterium
*2.A.9.5.2









Putative YidC of 236 aas and 4 or 5 TMSs.

Bacteria
Candidatus Beckwithbacteria
YidC of Candidatus Beckwithbacteria bacterium
*2.A.9.5.3









Putative YidC of 383 aas and 7 or 8 TMSs

Bacteria
Candidatus Shapirobacteria
YidC of Candidatus Shapirobacteria bacterium