PAUL A. LIEBMAN, M.D.

Professor of Biochemistry and Biophysics

143 Anatomy-Chemistry Building
(215) 898-6917
liebmanp@mail.med.upenn.edu

M.D. Johns Hopkins (1958)

DESCRIPTION OF RESEARCH INTERESTS:

Dr. Liebman's laboratory uses physical biochemical approaches to determine the mechanisms that control strength, speed and stability of signaling molecule interactions in hormone, neural and sensory signaling systems with emphasis on receptors, G proteins and membranes. The 7-transmembrane helix receptor (7TMHR) family initiates cell signaling events for thousands of hormones, pheromones and neuro-transmitters plus light, taste and smell stimuli. Each receptor requires a G protein signaling partner.

With a view to understand the molecular mechanics of all such systems, current work of Dr. Liebman's laboratory focuses on the most accessible of these systems, and studies: 1) the molecular coupling mechanism of visual transduction; 2) the mechanism of nucleotide activation of G proteins; 3) G protein ligand-dependent folding stability; 4) 7TMHR conformation, kinetics and stability; 5) the structural basis for receptor-arrestin and G protein recognition and effect of receptor phosphorylation; 6) the role of membrane protein embedding and surface charge in the above; and 7) the mechanism of anesthetic effect on signaling proteins. Specific thermodynamic, kinetic and structure questions and models are investigated through experiments utilizing computational modeling, UV-visible absorption, circular dichroism and tryptophan fluorescence spectroscopy, light scattering, calorimetry and radiotracers which are interpreted in light of static x-ray and NMR structures of the respective native proteins and activity of their misfunctional mutants.

Dr. Liebman is the originator and director of Biochem/Biophys 550, Molecular mechanisms of signal transduction and control.