Department of Human Biological Chemistry & Genetics, Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX 77555, USA.|Department of Human Biological Chemistry & Genetics, Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX 77555, USA.|Department of Human Biological Chemistry & Genetics, Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX 77555, USA.|Department of Human Biological Chemistry & Genetics, Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX 77555, USA.