[1] Univ Calif San Diego, Dept Pharmacol, La Jolla, CA 92093 USA
[2] Univ Calif San Diego, Dept Cellular & Mol Med, La Jolla, CA 92093 USA
[3] Univ Calif San Diego, Dept Chem & Biochem, La Jolla, CA 92093 USA
[4] Univ Calif San Diego, Howard Hughes Med Inst, La Jolla, CA 92093 USA
[5] Univ Illinois, Sect Digest Dis & Nutr, Dept Med, Chicago, IL 60612 USA
[6] Scripps Res Inst, Dept Cell Biol, La Jolla, CA 92037 USA
[7] Univ Toronto, Banting & Best Dept Med Res, Toronto, ON M5S 3E1, Canada
[8] Univ Toronto, Dept Med Genet & Microbiol, Toronto, ON M5S 3E1, Canada
[9] Genencor Inc, Dept Prot Engn, San Francisco, CA 94080 USA