SIFTS: Structure Integration with Function, Taxonomy and Sequences resource.
Velankar S, Dana JM, Jacobsen J, van Ginkel G, Gane PJ, Luo J, Oldfield TJ, O'Donovan C, Martin MJ, Kleywegt GJ. Nucleic Acids Res. 2013 Jan; 41(Database issue):D483-9. Epub 2012 Nov 29.