Suitable biological systems have been chosen with a view to utilizing image processing of electron micrographs as a means to visualize their protein structures and to identify changes associated with the respective biological functions. Four problem areas of varying degree of organizational complexity will be studied: isolated protein molecules, crystalline sheets of enzymes, lipoprotein membranes and regular phage structures which have been previously fruitfully utilized for 'conventional' image processing. Within each of these areas we have selected respectively, the product of the E. coli groE gene, urate oxidase, the envelope of vesicular stomatitis virus (VSV) and structures of the phi Cbk and T4 bacteriophages. The goal of the phage work will be to learn more of protein-protein interactions in assemblies of a single protein species. From phi Cbk tail we hope to learn how interprotein linkages are maintained as the tail flexes; from the extended and contracted T4 sheath structures we hope to identify some of the features of the conformational change that takes place during sheath contraction. The main thrust of the work will be to find methods to obtain regular lattices of molecules appropriate for high resolution structural studies in the electron microscope. Of special interest will be methods to obtain paracrystalline arrays of proteins within natural or synthetic membranes. Initially we will be concerned with a study of the surface organization of viral envelopes, particularly that of VSV. It is our hope that information about the viral envelope structure will aid attempts to understand the organization of membranes in general as well as the biogenetic principles involved in viral and membrane assembly.