Function and Biology

Mouse Tdt, F401A mutant, in complex with a DSB substrate, C-C base pair

Source organism: Mus musculus
Biochemical function: DNA binding
Biological process: DNA repair
Cellular component: not assigned

EC 2.7.7.31: DNA nucleotidylexotransferase

Reaction catalysed:
Deoxynucleoside triphosphate + DNA(n) = diphosphate + DNA(n+1)
Systematic name:
Nucleoside-triphosphate:DNA deoxynucleotidylexotransferase
Alternative Name(s):
  • Addase
  • Deoxynucleotidyl terminal transferase
  • Deoxyribonucleic acid nucleotidyltransferase
  • Deoxyribonucleic nucleotidyltransferase
  • TdT
  • Terminal addition enzyme
  • Terminal deoxynucleotide transferase
  • Terminal deoxynucleotidyltransferase
  • Terminal deoxyribonucleotidyltransferase
  • Terminal transferase

GO terms

Biochemical function:
Biological process:
Cellular component:
  • not assigned

Sequence families

Pfam Protein families (Pfam)
PF14791
Domain description: DNA polymerase beta thumb
Occurring in:
  1. DNA nucleotidylexotransferase

PF10391
Domain description: Fingers domain of DNA polymerase lambda
Occurring in:
  1. DNA nucleotidylexotransferase

PF14716
Domain description: Helix-hairpin-helix domain
Occurring in:
  1. DNA nucleotidylexotransferase

PF01909
Domain description: Nucleotidyltransferase domain
Occurring in:
  1. DNA nucleotidylexotransferase

InterPro InterPro annotations
IPR001726
Domain description: DNA nucleotidylexotransferase (TdT) / DNA-directed DNA/RNA polymerase mu
Occurring in:
  1. DNA nucleotidylexotransferase
IPR022312
Domain description: DNA polymerase family X
Occurring in:
  1. DNA nucleotidylexotransferase
IPR027421
Domain description: DNA polymerase lambda lyase domain superfamily
Occurring in:
  1. DNA nucleotidylexotransferase
IPR002054
Domain description: DNA-directed DNA polymerase X
Occurring in:
  1. DNA nucleotidylexotransferase
IPR010996
Domain description: DNA polymerase beta-like, N-terminal domain
Occurring in:
  1. DNA nucleotidylexotransferase
IPR028207
Domain description: DNA polymerase beta, palm domain
Occurring in:
  1. DNA nucleotidylexotransferase
IPR037160
Domain description: DNA polymerase, thumb domain superfamily
Occurring in:
  1. DNA nucleotidylexotransferase
IPR029398
Domain description: DNA polymerase beta, thumb domain
Occurring in:
  1. DNA nucleotidylexotransferase
IPR018944
Domain description: DNA polymerase lambda, fingers domain
Occurring in:
  1. DNA nucleotidylexotransferase

Structure domains

CATH CATH domains
3.30.210.10
Class: Alpha Beta
Architecture: 2-Layer Sandwich
Topology: Beta Polymerase; domain 3
Homology: DNA polymerase, thumb domain
Occurring in:
  1. DNA nucleotidylexotransferase
1.10.150.20
Class: Mainly Alpha
Architecture: Orthogonal Bundle
Topology: DNA polymerase; domain 1
Homology: 5' to 3' exonuclease, C-terminal subdomain
Occurring in:
  1. DNA nucleotidylexotransferase
3.30.460.10
Class: Alpha Beta
Architecture: 2-Layer Sandwich
Topology: Beta Polymerase; domain 2
Homology: Beta Polymerase, domain 2
Occurring in:
  1. DNA nucleotidylexotransferase
1.10.150.110
Class: Mainly Alpha
Architecture: Orthogonal Bundle
Topology: DNA polymerase; domain 1
Homology: DNA polymerase beta, N-terminal domain-like
Occurring in:
  1. DNA nucleotidylexotransferase