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What is InterPro ?

InterPro is an integrated database of predictive protein "signatures" used for the classification and automatic annotation of proteins and genomes. InterPro classifies sequences at superfamily, family and subfamily levels, predicting the occurrence of functional domains, repeats and important sites. InterPro adds in-depth annotation, including GO terms, to the protein signatures.

More: http://www.ebi.ac.uk/interpro/

Reference: Hunter S, et al. InterPro: the integrative protein signature database. Nucleic Acids Res. 2009 Jan;37(Database issue):D211-5. Epub 2008 Oct 21.

Which databases are used in InterPro ?

InterPro combines a number of databases (referred to as member databases) that use different methodologies and a varying degree of biological information on well-characterised proteins to derive protein signatures. By uniting the member databases, InterPro capitalises on their individual strengths, producing a powerful integrated database and diagnostic tool (InterProScan).

The member databases use a number of approaches:

  • ProDom: provider of sequence-clusters built from UniProtKB using PSI-BLAST.
  • PROSITE patterns: provider of simple regular expressions.
  • PROSITE and HAMAP profiles: provide sequence matrices.
  • PRINTS provider of fingerprints, which are groups of aligned, un-weighted Position Specific Sequence Matrices (PSSMs).
  • PANTHER, PIRSF, Pfam, SMART, TIGRFAMs, Gene3D and SUPERFAMILY: providers of hidden Markov models (HMMs).

Diagnostically, these resources have different areas of optimum application owing to the different underlying analysis methods. In terms of family coverage, the protein signature databases are similar in size but differ in content. While all of the methods share a common interest in protein sequence classification, some focus on divergent domains (e.g., Pfam), some focus on functional sites (e.g., PROSITE), and others focus on families, specialising in hierarchical definitions from superfamily down to subfamily levels in order to pin-point specific functions (e.g., PRINTS). TIGRFAMs focus on building HMMs for functionally equivalent proteins and PIRSF always produces HMMs over the full length of a protein and have protein length restrictions to gather family members. HAMAP profiles are manually created by expert curators they identify proteins that are part of well-conserved bacterial, archaeal and plastid-encoded proteins families or subfamilies. PANTHER build HMMs based on the divergence of function within families. SUPERFAMILY and Gene3D are based on structure using the SCOP and CATH superfamilies, respectively, as a basis for building HMMs.

How to read InterProScan results

  • IP id: Identifier of the InterPro family. Click on it to access to the full description of the InterPro entry.
  • Method: Method used in obtaining the result. It corresponds to one of the member databases.
  • Method id: Identifier of the member database family that generated the result. Click on it to access to the full description of the family.
  • Method description: Generic name associated with the InterPro family description
  • Begin: Begin of the match on the sequence
  • End: End of the match on the sequence
  • Eval: Evalue
  • IP description: Description of the InterPro family
  • IP GO: Gene Ontology terms associated with the InterPro family