By using a conventional two-hybrid technique with an Src homology 3 (SH3) domain of Nesh as the bait protein, a novel full-length cDNA was isolated and sequenced from a human placenta cDNA library. This cDNA consists of 3023 bp and has a predicted open reading frame that encodes 486 amino acids. It possesses an SH3 binding motif, a nuclear targeting sequence, and no catalytic domain. Overall, it has no similarity to known molecules involved in a signaling cascade. Polymerase Chair reaction-based mapping with both a monochromosomal hybrid panel and radiation hybrid cell panels localized the gene on human chromosome 3q12 near the marker D3S1271.