We have determined the sequence of the Neurospora crassa met-10+ gene and its flanking regions, and have isolated and analyzed cDNA clones for this region. We have identified two closely linked genes transcribed in the same orientation. The met-10+ gene is the downstream gene; an open reading frame (ORF) derived from five exons encodes a 475-amino-acid protein. The deduced protein lacks similarity to other characterized proteins. However, it exhibits a strong similarity to the product of an ORF of unknown function on Saccharomyces cerevisiae chromosome 8. This sequence similarity suggests functional equivalence and should facilitate identification of the function of met-10+ using gene disruptions in S. cerevisiae.