UniProt, the world’s largest protein database, is now available under terms of the Creative Commons Attribution-NoDerivs 2.5 License.

Please see Science Commons’ database licensing FAQ concerning which elements of the database are under copyright and which are not.

The UniProt background page explains what the database is all about:

Protein sequence databases have become a crucial resource for molecular biologists, both as repositories for protein functional and structural data and as starting points for future experiments. The UniProt consortium aims to support biological research by maintaining a high quality database that serves as a stable, comprehensive, fully classified, richly and accurately annotated protein sequence knowledgebase, with extensive cross-references and querying interfaces freely accessible to the scientific community.