Production of recombinant products of pharmaceutical and industrial importance in a variety of microorganisms has yielded a wide variety of biologically active proteins. Fungi offer the advantage of reduced culturing and downstream processing cost because they are capable of secreting prodigious quantities of protein. The genetics and biochemistry of Neurospora crassa are the most fully characterized of the filamentious fungi. The development of a high activity, efficient secretion expression vector system for N. crassa will facilitate efficient production of heterologous proteins in this fungus. This proposal aims to identify and clone an abundantly secreted native protein of N. crassa and characterize its promoter and secretion signal. The new N. crassa expression and secretion vectors capable of producing high levels of secreted recombinant proteins.