9458207 Bowie Membrane proteins are responsible for the selective transport of molecules in and out of the cell, for coupling of energy from nutrient metabolism or light to the synthesis of ATP, and for transducing external signals from molecules such as neurotransmitters and hormones across the membrane. Mutations in membrane proteins are responsible for diseases ranging from cystic fibrosis to cancer. In spite of their crucial importance to biochemical processes, knowledge of membrane protein structure is still at a rudimentary level. In order to understand how the amino acid sequence of a membrane protein determines its three-dimensional structure, it is essential to know which residues in the sequence are the key determinants of that structure. The work undertaken in this study is designed to identify the structure determining residues in the sequence of a particular membrane protein, diacylglycerolkinase from Escherichia coli. The problem will be addressed by determining what sequence changes can be made in the protein without affecting activity, what sequence changes destroy the ability of the protein to fold and function, and what sequence changes alter the stability of the protein. Residues important to the structure of the protein should be less tolerant to change than residues that are not playing crucial roles. The information obtained will improve the understanding of the forces that stabilize membrane protein structure and improve the ability to predict membrane protein structure. %%% Proteins are enormous molecules that are almost entirely responsible for the smooth operation of cellular machinery. Many thousands of different protein molecules are required to create an organism as complex as the human body and some of our most feared diseases ranging from cystic fibrosis to cancer are caused by damaged protein molecules. Consequently, much effort has been directed toward learning how particular protein molecules work. A crucial step in developing an understanding of any individual protein is to determine its structure: the three dimensional arrangement of atoms in the protein molecule. Using current experimental approaches, however, it usually takes many years to determine the structure of any protein. As a result, there is little hope of obtaining a detailed understanding of the thousands of proteins in the cell unless we can more rapidly learn their structures. This work is directed toward understanding the molecular rules that determine how a particular class of protein structures is determined. This work will be used to develop more rapid, theoretical approaches to structure determination. ***
