Joint Center for Structural Genomics, La Jolla, CA 92037, USA.|Joint Center for Structural Genomics, La Jolla, CA 92037, USA.|Joint Center for Structural Genomics, La Jolla, CA 92037, USA.|Joint Center for Structural Genomics, La Jolla, CA 92037, USA.|Joint Center for Structural Genomics, La Jolla, CA 92037, USA.|Joint Center for Structural Genomics, La Jolla, CA 92037, USA.