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11810  structures 9013  species 0  interactions 149295  sequences 1293  architectures

Clan: NTN (CL0052)


NTN hydrolase superfamily Add an annotation

In the N-terminal nucleophile aminohydrolases (Ntn hydrolases) the N-terminal residue provides two catalytic groups, nucleophile and proton donor. These enzymes use the side chain of the amino-terminal residue, incorporated in a beta-sheet, as the nucleophile in the catalytic attack at the carbonyl carbon. The nucleophile is cysteine in GAT, serine in penicillin acylase, and threonine in the proteasome. All the enzymes share an unusual fold in which the nucleophile and other catalytic groups occupy equivalent sites. This fold provides both the capacity for nucleophilic attack and the possibility of autocatalytic processing [1].

This clan contains 17 families and the total number of domains in the clan is 149295. The clan was built by A Bateman.

Literature references

  1. Brannigan JA, Dodson G, Duggleby HJ, Moody PC, Smith JL, Tomchick DR, Murzin AG; , Nature 1995;378:416-419.: A protein catalytic framework with an N-terminal nucleophile is capable of self-activation. PUBMED:7477383 EPMC:7477383
  2. Ginalski K, von Grotthuss M, Grishin NV, Rychlewski L; , Nucleic Acids Res. 2004;32:576-581.: Detecting distant homology with Meta-BASIC. PUBMED:15215454 EPMC:15215454
  3. Pei J, Grishin NV; , Protein Sci 2003;12:1131-1135.: Peptidase family U34 belongs to the superfamily of N-terminal nucleophile hydrolases. PUBMED:12717035 EPMC:12717035


This clan contains the following 17 member families:

AAT Asparaginase_2 CarA_N CBAH DUF3700 G_glu_transpept GATase_2 GATase_4 GATase_6 GATase_7 IMP_cyclohyd Penicil_amidase Peptidase_C69 Phospholip_B Proteasome Proteasome_A_N TANGO2

External database links

Domain organisation

Below is a listing of the unique domain organisations or architectures from this clan. More...

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The table below shows the number of occurrences of each domain throughout the sequence database. More...

Pfam family Num. domains Alignment
Proteasome (PF00227) 39483 (26.4%) View
GATase_6 (PF13522) 18163 (12.2%) View
GATase_7 (PF13537) 17314 (11.6%) View
G_glu_transpept (PF01019) 17240 (11.5%) View
Proteasome_A_N (PF10584) 12632 (8.5%) View
GATase_2 (PF00310) 8954 (6.0%) View
Asparaginase_2 (PF01112) 8907 (6.0%) View
Penicil_amidase (PF01804) 5513 (3.7%) View
TANGO2 (PF05742) 4233 (2.8%) View
GATase_4 (PF13230) 3768 (2.5%) View
CBAH (PF02275) 3269 (2.2%) View
AAT (PF03417) 3092 (2.1%) View
Peptidase_C69 (PF03577) 2870 (1.9%) View
Phospholip_B (PF04916) 1856 (1.2%) View
DUF3700 (PF12481) 1363 (0.9%) View
IMP_cyclohyd (PF07826) 626 (0.4%) View
CarA_N (PF09147) 12 (0.0%) View
Total: 17 Total: 149295 Clan alignment

Please note: Clan alignments can be very large and can cause problems for some browsers. Read the note above before viewing.

Family relationships

This diagram shows the relationships between members of this clan. More...

Species distribution

Tree controls


This tree shows the occurrence of the domains in this clan across different species. More...



For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the MSD group, to allow us to map Pfam domains onto UniProt three-dimensional structures. The table below shows the mapping between the Pfam families in this clan, the corresponding UniProt entries, and the region of the three-dimensional structures that are available for that sequence.

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