Principal Investigators of TEMIMPS:
Seven different laboratories from across the United States participate in TEMIMPS. Investigators from these laboratories have established expertise in electron cryo-microscopy, electron crystallography and/or membrane proteins.

David Stokes, Ph.D. - TEMIMPS PI
NYU Medical Center, Skirball Institute
& New York Structural Biology Center
Dr. Stokes' experience in electron microscopy dates back to his undergraduate research at the University of California at Berkeley, during which time he developed software for analyzing elemental mapping using energy dispersive X-ray detector in an SEM. Since then, Dr. Stokes has training with some of the pioneers of the field of TEM: David DeRosier, Richard Henderson, Nigel Unwin. After studying the variable twist of actin for his Ph.D. at Brandeis University, Dr. Stokes started working with membrane protein crystals as a postdoctoral fellow at the Laboratory of Molecular Biology. This work includes developing methods for reconstitution and crystallization as well as structure determination of ATP-driven ion pumps during faculty appointments at the University of Virginia and at New York University, where he continues to run a laboratory in the Skirball Institute of Biomolecular Medicine. Dr. Stokes became director of cryo-electron microscopy at the New York Structural Biology Center in 2002 and now supervises a diverse portfolio of projects including tomography, single particle analysis and electron crystallography.

Iban Ubarretxena-Belandia,Ph.D. - TEMIMPS Co-PI
Mount Sinai School of Medicine
Dept. of Structural and Chemical Biology
Dr. Ubarretxena-Belandia is an experienced membrane protein structural biologist. He obtained his PhD in membrane protein biochemistry with Drs. Niek Dekker and Gerard de Haas at Utrecht University. His PhD involved studying the biochemistry of membrane enzymes and producing them for X-ray crystallographic studies. He later trained in membrane biophysics with Dr. Don Engelman (Yale University) and in membrane protein electron crystallography with Drs. Richard Henderson and Chris Tate (MRC Laboratory of Molecular Biology). Dr. Ubarretxena is currently an assistant professor in the Department of Structural and Chemical Biology at Mount Sinai School of Medicine. His laboratory studies intramembrane proteases, a new family of membrane proteins that are pivotal in human biology and disease. The laboratory is also involved in developing and applying electron crystallography to solve the structures of membrane proteins in their native lipid bilayer environment. In 2006 Dr. Ubarretxena-Belandia was a recipient of a Career Award from the National Science Foundation.

Tom Walz, Ph.D. - TEMIMPS Co-PI
Harvard Medical School
Department of Cell Biology
Dr. Walz has had a career-long interest in electron crystallography to study membrane proteins and, in particular, aquaporins (AQPs). As a graduate student with Andreas Engel at the University of Basel, he worked on AQP1, thus contributing to the first atomic structure of a water channel. As a postdoc with Per Bullough at the University of Sheffield, he worked on 2D crystals of several photosynthetic proteins. After joining the faculty at Harvard Medical School in 1999, he participated in the determination of the atomic structure of AQP4 and later AQP0, eventually producing a structure of AQP0 together with Tamir Gonen at 1.9 A resolution. He is currently using AQP0 as a platform to study systematically the interaction of various lipid species with this protein and has an active portfolio of EM projects involving both electron crystallography and single particle analysis.

Andreas Engel, Ph.D. - TEMIMPS Co-PI
Case Western Reserve Univerisity
Department of Pharmacology
Andreas Engel received his PhD in Laser Physics & Holography in Switzerland. After postdoctoral studies at the Johns Hopkins University, Baltimore, he built up a Scanning Transmission Electron Microscope (STEM) at the Biozentrum in University of Basel, Switzerland. Still active, the Basel STEM group has made important contributions over more than three decades. Since 1980 Andreas Engel worked on membrane protein structure and dynamics using STEM, electron crystallography, and later atomic force microscopy (AFM). He contributed to early work on the 3D structure of bacterial porin OmpF, to the development of 2D crystallization of membrane proteins, and to the elucidation of the human aquaporin-1, whose structure was solved in 2000 during a fruitful collaboration with Peter Agre and Yoshi Fujiyoshi. More recently, the packing of rhodopsin in rows of dimers has been observed in native disc membranes using AFM in a collaborative effort with Kris Palczewski. After an industry appointment Andreas Engel joined Ueli Aebi in 1986 to build up the Maurice E. Müller Institute for Structural Biology and to join the faculty of the Biozentrum. In 2008 Andreas Engel accepted the invitation of the Department of Pharmacology at Case Western Reserve University to help establishing cryo-electron microscopy and 3D-EM at the Cleveland Center for Structural and Membrane Biology.

Pawel Penczek, Ph.D. - TEMIMPS Co-PI
University of Texas
Houston Medical School
Dr. Penczek’s interest in biomedical digital signal processing began during his studies at the Physics Department of Warsaw University, Poland. His undergraduate research was on analysis of scintigraphic images, while his PhD was on the analysis of multi-channel electroencephalographic data. He became a postdoctoral fellow with Joachim Frank in Wadsworth Center, Albany NY, where he participated in the first cryo-EM determination of the structure of E.coli ribosome in 1989. During his tenure in Dr. Frank’s group he contributed novel single particle computational methods to widely used package SPIDER. Subsequently, in 2000 he became a faculty at The University of Texas, Houston Medical School, where he continues development of computational methodology for high-resolution single particle EM, particularly in the presence of conformational heterogeneity. In the last decade he developed, in collaboration with others, a modern single particle software package SPARX. He is also a director of the Structural Biology Imaging Center at UT Houston.

Tamir Gonen, Ph.D. - TEMIMPS Affiliate
Janelia Farms Research Campus
Howard Hughes Medical Institute
Tamir Gonen began studying membrane protein structure and function as a doctorate student in New Zealand working with Ted Baker and Joerg Kistler. The research focused on lens membrane proteins, in particular, X-ray crystallography of MIP (Aquaporin-0, AQP0) and electron microscopy and biochemistry of MP20. Using membrane proteomics Gonen discovered a new adhesion modulator in the lens called Galectin-3 that bound MP20 and mediated junction formation. During his doctoral studies, Dr Gonen traveled on a number of occasions to the laboratory of Thomas Walz at Harvard Medical School where he worked with Yifan Cheng (now at UCSF) and used electron microscopy to study the structure of the lens MP20. Upon graduation, he joined the Walz laboratory to carry on with structure analysis of lens membrane proteins this time focusing more on AQP0. Shortly after growing double-layered 2D crystals of AQP0, he traveled with Tom and Yifan to Japan to collaborate with Yoshinori Fujiyoshi of Kyoto University and to determine the structure of AQP0 by electron diffraction. In 2005 Gonen opened his own laboratory at the University of Washington in Seattle where he directs the cryo EM laboratory. In 2009 Gonen was a recipient of a Career Development Award from the American Diabetes Association and he also became an Early Career Scientist at the Howard Hughes Medical Institute. His current laboratory is on the HHMI campus in Janelia Farms, where he studies the structure and function of membrane proteins that are involved in diverse medical diseases.