Structure and Function of Membrane Proteins

Communication between nerve cells serves as the basis of all brain activity, and one of the fundamental steps involved in signal transmission between the nerve cells, is the conversion of a "chemical" signal liberated at the end of one nerve cell, into an "electrical" signal at the second nerve cell. This step is mediated by a class of membrane bound proteins known as neurotransmitter receptors. Glutamate receptors belong to this family of proteins, and are the main excitatory receptors in the central nervous system.

Our laboratory is interested in gaining an understanding of agonist mediated activation and desensitization of this receptor by determining the structural changes in the protein induced by agonist binding. This is achieved by using various cutting edge spectroscopic methods that allow the characterization of the dynamic state structure of the proteins at a significantly higher resolution than X-ray structures. The structural changes thus determined are correlated to the functional consequences as measured by electrophysiological measurements. These investigations provide a detailed understanding of the agonist controlled function of the glutamate receptors and hence aid in the rational design of drugs targeting this group of important proteins that are involved in diverse neuropathologies, such as epilepsy and ischemia.

We have used absorption spectroscopy to establish that the local structure of the ligand binding site is the same in the isolated ligand binding domain (SIS2 protein) as that in the native glutamate receptor, thus validating the detailed structure/function relation-ships that have been developed based on a comparison of the structure of the isolated ligand binding domain and electro-physiological consequences in the native receptor.