The interactions between neurons in the formation of a synaptic contact are poorly understood. When a potential target is contacted by an axonal growth cone, it initiates formation of a presynaptic terminal. Dr. Burry will examine proteins that may be involved in the initiation and maintenance of this important cell.cell interaction. The working hypothesis of the research project is that developmentally regulated proteins are up regulated during neuritic outgrowth, and that these proteins are present at the growth cone.target contact. The experiments to be carried out will study the growth associated protein, GAP.43, and two synaptic vesicle proteins, p65 and synapsin I, to determine if their subcellular distribution and their time of appearance is consistent with classification as developmentally regulated proteins. Immunocytochemistry will be performed with 10 um section examined in a confocal scanning laser microscope, with 0.5 um frozen sections examined with epifluorescence, and silver intensified 1 nm gold for the electron microscope. One of the main reasons for the slow progress in the understanding of mechanisms involved in synaptogenesis has been the inability to identify developmentally regulated proteins. The planned experiments will generate monoclonal antibodies to developmentally regulated proteins by combining the use of enriched antigen sources and newly developed immunization protocols.