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410  structures 6695  species 8  interactions 35500  sequences 419  architectures

Clan: HSP20 (CL0190)


HSP20-like chaperone superfamily Add an annotation

The small heat shock proteins (sHSPs) prevent protein aggregation during heat shock and oppose regulated cell death. A conserved arginine residue in the HSP20/alpha-crystallin domain (Pfam:PF00011) has in fact been implicated in the development of cataracts and myopathies [1]. The CS family (Pfam:PF04969) includes proteins that are known to bind HSP90 [2], as well as p23 (Swiss:Q15185), which is an HSP90 co-chaperone [3].

This clan contains 6 families and the total number of domains in the clan is 35500. The clan was built by M Fenech.

Literature references

  1. van Montfort RL, Basha E, Friedrich KL, Slingsby C, Vierling E; , Nat Struct Biol 2001;8:1025-1030.: Crystal structure and assembly of a eukaryotic small heat shock protein. PUBMED:11702068 EPMC:11702068
  2. Lee YT, Jacob J, Michowski W, Nowotny M, Kuznicki J, Chazin WJ; , J Biol Chem 2004;279:16511-16517.: Human Sgt1 binds HSP90 through the CHORD-Sgt1 domain and not the tetratricopeptide repeat domain. PUBMED:14761955 EPMC:14761955
  3. Weaver AJ, Sullivan WP, Felts SJ, Owen BA, Toft DO; , J Biol Chem 2000;275:23045-23052.: Crystal structure and activity of human p23, a heat shock protein 90 co-chaperone. PUBMED:10811660 EPMC:10811660


This clan contains the following 6 member families:

ArsA_HSP20 CS GvpH HSP20 PIH1_CS Pih1_fungal_CS

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
HSP20 (PF00011) 23801 (67.0%) View
CS (PF04969) 8899 (25.1%) View
ArsA_HSP20 (PF17886) 1538 (4.3%) View
PIH1_CS (PF18201) 1173 (3.3%) View
Pih1_fungal_CS (PF18482) 46 (0.1%) View
GvpH (PF05455) 43 (0.1%) View
Total: 6 Total: 35500 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...



There are 8 interactions for this clan. More...

Interacting families
Crystallin HSP20
HATPase_c_3 CS
Siah-Interact_N CS


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.

Loading structure mapping...