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A list of the 11 two-component and 3 three-component type II TA families that encompass the full set of current TADB entries that have to date been mapped to a specific family. The type II TA family classification system used is based on that described in the reviews by Gerdes et al. (2005) and Van Melderen et al.(2009). Click here for more details about the typye II TA family classification system.

# TA family Toxin Antitoxin Toxin target Reference Notes
1 ccd CcdB CcdA DNA gyrase [Replication] Jaffé et al, 1985
F1 Plasmid
2 hicBA HicA HicB RNA cleavage Makarova et al, 2006
Jørgensen et al, 2009
3 hipBA HipA HipB phosphorylate EF-Tu [Translation] Black et al, 1991
4 mazEF(chpA) MazF(ChpAK) MazE(ChpAI) mRNA cleavage [Translation] Masuda et al, 1993
Chromosomal homologues of parD
5 parD (PemKI) Kid(PemK) Kis(PemI) mRNA cleavage [Translation] Hargreaves et al, 2002
R1⁄R100 plasmid
6 parDE ParE ParD DNA gyrase [Replication] Jensen et al, 1995
RK2⁄RP4 plasmid
7 phd-doc Doc Phd Ribosome
Lehnherr et al, 1993
Doc indirectly causes mRNA cleavage via activating the relBE system
8 relBE RelE RelB Ribosome [Translation] Gotfredsen et al, 1998
This family contains five subfamilies: relBE, higBA (Christensen-Dalsgaard et al., 2010), yfeM-yoeB (Kamada et al., 2005), ygiTU(mgsAR) (Brown et al., 2009) and prlF-yhaV (Schmidt et al., 2007).
9 vapBC (vag) VapC VapB RNAs Pullinger et al, 1992
Zhang et al, 2004
vapC codes for endoribonuclease. This family contains two subfamilies: yapBC and bat-bto (Miclea et al., 2010).
10 mosAT mosT mosA N/D Wozniak et al, 2009
mosAT promotes the maintenance of an integrative conjugative element SXT
11 yeeUV yeeV yeeU N/D Brown et al, 2003
# TA family Toxin Antitoxin Regulator Reference Notes
12 ω-ε-ζ ζ zeta ε epsilon ω omega Zielenkiewicz et al, 2005
ζ zeta codes for phosphotransferase
13 pasABC PasB PasA PasC Smith et al, 1998
14 paaR-paaA-parE ParE PaaA paaE Hallez et al, 2010
TADB v1.1 now includes the 6757 TA loci found in 750 genomes reported by Makarova et al.(2009) have been organized into the 44 toxin-antitoxin domain pair groupings. Click here for more details about the TA domain pair system.

# TA pair T-domain AT-domain Notes
1 Xre-HipA HipA Xre
2 Xre-COG5654 COG5654 Xre
3 Xre-COG2856 COG2856 Xre T : predicted Zn-dependent protease. Often fused to AT domain. Frequent association with RelE and PIN toxins
4 Xre-Bro Bro Xre
5 Xre-YgiU YgiU Xre T: motility quorum-sensing regulator mqsR
6 Xre-DUF397 DUF397 Xre T: no prediction; molecular mechanism unknown
7 Xre-Fic Fic Xre
8 Xre-PIN PIN Xre
9 Xre-MazF MazF Xre
10 Xre-GNAT GNAT Xre The closest characterized GNAT family acetyltrasferase is involved in antibiotic resistance
11 Xre-RelE RelE Xre
12 COG5606-RelE RelE COG5606
13 RHH-RelE RelE RHH Specific for methanogens; AT : predicted RHH superfamily protein
14 AbrB-RelE RelE AbrB
15 PHD-RelE RelE PHD
16 RHH-COG2929 COG2929 RHH
17 RHH-GNAT GNAT RHH T : is GNAT family acetyltrasferase
18 RHH-Fic Fic RHH
20 RHH-MazF MazF RHH
21 XF1863-MazF MazF XF1863 No prediction for AT
22 PHD-MazF MazF PHD
23 AbrB-MazF MazF AbrB
24 AbrB-Fic Fic AbrB
25 AbrB-PIN PIN AbrB
26 MerR-PIN PIN MerR AT: truncated MerR
27 COG2442-PIN PIN COG2442 Structure of AT is solved (PDB:2ga1):DNA/RNA-binding 3-helical bundle
28 COG2886-PIN PIN COG2886
30 PHD-Fic Fic PHD
31 HicB-HicA HicA HicB
32 HEPN-MNT MNT HEPN MNT - minimal nucleotidyltransferase, possible toxin; HEPN - possible substrate binding domain; Structure solved (MNT: 1no5 and HEPN: 1o3u and 1jog). Molecular mechanism unknown.
33 ArsR-COG3832 COG3832 ArsR T : Cyclase/dehydratase family protein. (PDB: 1xuv) START domain superfamily
34 YhfG-Fic Fic YhfG AT : is predicted DNA-binding protein; Specific for enteroproteobacteria
35 Xre-COG3832 COG3832 Xre
36 COG2886-RelE RelE COG2886
37 Xre-COG2929 COG2929 Xre
38 COG5304-COG2929 COG2929 COG5304 AT: COG5304 and COG3514 Families. AT: predicted RHH family protein; Molecular mechanism unknown.
39 PHD-MazFn MazFn PHD
40 COG1753-PIN PIN COG1753 AT: RHH (RHH); Specific for archaea
41 COG2880-PIN PIN COG2880 Structure of AT is solved (PDB:2nwt); related to AbrB superfamily
42 PHD-SMa0917 SMa0917 PHD T : predicted MazF superfamily protein; Molecular mechanism is likely the same as for MazF toxin
43 COG5606-COG4679 COG4679 COG5606 AT: predicted HTH domain; T : predicted RelE superfamily protein
44 COG5642-COG5654 COG5654 COG5642 AT : xre family HTH; T : RES domain; Molecular mechanism unknown.