We previously reported a nearly 1-Mb contig of cosmid and YAC clones at D10S102, a locus that is tightly linked to the gene responsible for multiple endocrine neoplasia type 2 (MEN2A). Subclones of 159 genomic EcoRI fragments in the contig were tested on "zoo blot" to detect DNA sequences conserved in various species. Nine fragments found to contain conserved sequences were used as probes for screening cDNA libraries. One of these probes, y300-pL50, recognized a cDNA from a human fetal brain library. The cDNA encoded a protein consisting of 270 amino acids, whose predicted sequence has a high degree of homology to heterogeneous nuclear ribonuclear protein. This expressed sequence may be a candidate for the gene responsible for MEN2A.