The long term objective of this proposal is to understand how genomic information is utilized to direct developmental processes. These processes are believed to be regulated by genes which become active in a stage-specific fashion. Among several stage-specific or developmentally regulated genes that we have isolated from our cDNA libraries and characterized, one gene, p2- 4, which represents a new unidentified gene, encodes a polypeptide of about 50kd and appears to participate in organogenesis of certain tissues during fetal development. The expression of this gene is not only developmentally regulated during embryogenesis but also tissue-specific. We will isolate cDNA clones which produce p2-4 specific protein. The protein will be used to produce antibodies which will then be used to determine whether the p2-4 protein is an extracellular matrix protein, an intracellular molecule or a cell surface molecule. Specific cell types expressing p2-4 protein will also be determine. Antibodies will also be used to investigate the biochemical properties of the protein. The temporal appearance of p2-4 transcript in the embryo and the possible presence of a second gene member will be elucidated. Furthermore, the function of the protein will be explored by the use of antibodies. The regulation of p2-4 gene expression will also be studied and its transcription regulatory region will be isolated for use as a tool to isolate transcription regulatory genes in future research. These experiments should provide information about the role of p2-4 gene in mammalian development and about the lineage history of the cells and organs expressing this gene during fetal development. They should also contribute to an understanding of the molecular basis of development.