The primary goal of the research program is to contribute to a molecular definition, and consequently deeper functional understanding of the synapse. A secondary goal which takes advantage of the reagents we are preparing in executing our primary goal is to contribute to an understanding of how the expression of neuronal specific genes are regulated spatially and temporally. Our objectives for this project period are: 1. Determination of the function of the F1-20 antigen, a novel synapse specific, developmentally regulated, neuronal specific protein in the murine CNS. Recently we have found that the F1-20 antigen is a substrate for neuronal calpain. Furthermore, we have also recently determined that the F1-20 antigen is a phosphoprotein. The possible implications of these new results for the function of the F1-20 antigen will also be explored. 2. Initial assessment of the genomic DNA sequences which are required to effect accurate cell-type specific and temporal regulation of the F1-20 gene. This will be carried out in transgenic mice, as the first step towards a longer range effort to understand the regulation of gene expression in neuronal cells. 3. Characterization of the F2-30 antigen, a novel neuronal specific protein expressed in a regionally restricted fashion within the CNS during embryogenesis. We will complete our characterization of the F2-30 cDNA, and test the hypothesis based n a homology between the deduced amino acid sequence with type III fibronectin domains that the F2-30 antigen play a role in the establishment of specific synaptic connections.