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1  structure 11224  species 0  interactions 16069  sequences 15  architectures

Clan: T3SS-hook (CL0424)


Type III secretion system-derived superfamily, hook-related Add an annotation

There is homology between the proteins forming the flagellar system and those involved in translocation of effector proteins at host-infection. Both systems, in Gram-negative bacteria, are Sec-independent but ATPase-dependent. There are up to 9 proteins that are homologous between the two systems. It is not clear, however, why HpaP proteins, which are essentially suppressants of HrpB2, an essential pathogenicity factor, should also be homologous to any of these families.

This clan contains 3 families and the total number of domains in the clan is 16069. The clan was built by P Coggill.

Literature references

  1. Desvaux M, Hebraud M, Henderson IR, Pallen MJ;, Trends Microbiol. 2006;14:157-160.: Type III secretion: what's in a name?. PUBMED:16533600 EPMC:16533600


This clan contains the following 3 member families:

DUF721 Flg_hook HpaP

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
Flg_hook (PF02120) 9033 (56.2%) View
DUF721 (PF05258) 6889 (42.9%) View
HpaP (PF09483) 147 (0.9%) View
Total: 3 Total: 16069 Clan alignment

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Family relationships

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

Species distribution

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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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