InterPro is a database of protein families, domains and functional sites in which identifiable features found in known proteins can be applied to unknown protein sequences.

UniProt (Universal Protein Resource) is the world's most comprehensive catalogue of information on proteins. It is a central repository of protein sequence and function created by joining the information contained in UniProtKB/Swiss-Prot, UniProtKB/TrEMBL, and PIR.

Expasy server for Uniprot

Online text-based search and retrieval system used at NCBI for finding proteins by keywords, id number, database number, etc. The protein entries in the Entrez search and retrieval system have been compiled from a variety of sources, including SwissProt, PIR, PRF, PDB, and translations from annotated coding regions in GenBank and RefSeq.

Uniprot Text search (note: search soon available on uniprot home)

Multiple search entries on Uniprto/SwissProt/TrEMBL

SIRW is a web interface to SIR (Simple Indexing and Retrieval System). SIR provides the ability to simultaneously search a protein database with a sequence motif pattern and keywords, e.g. useful for restricting a pattern search to a database subset.

Information Hyperlinked over Proteins. A protein data harvester.

Recent Hits Acquired from BLAST (ReHAB) is a tool for finding new protein hits in repeated PSI-BLAST searches. ReHAB compares results from PSI-BLAST searches performed with two versions of a protein sequence database and highlights hits that are present only in the updated database.

Database of cognate ligands for the domains of enzyme structures in CATH, SCOP and Pfam.