Membrane proteins play a variety of critical roles in cellular metabolism and physiology. However, little is known about the process of protein insertion into the membrane and of the assembly of these proteins into functional structures. One class of membrane proteins, the ATP binding cassette (ABC) superfamily, includes, the bacterial binding protein-dependent transporters, the yeast STE6, and the cystic fibrosis gene protein. This proposed study will examine the structure and assembly process for membrane proteins using the ABC transporter involved in maltose uptake in Escherichia coli as a model system. This work will take advantage the extensive genetic characterization that has been done on the mal genes which code for these proteins, of a biochemical assay for tracking the in vivo assembly of the hetero-oligomeric maltose transport complex, and of the gene fusion methodologies available in E. coli. %%% This work will test these different models for the assembly of complex membrane proteins and, when appropriate, lead to the proposal of different or revised models for membrane protein folding. The results from these studies will contribute to a greater understanding of the in vivo structure and assembly of membrane proteins.
