DA41 was previously identified as one of the DAN-binding proteins, via a yeast-based two-hybrid screening strategy. In the present study, we cloned a human homolog of DA41 cDNA. Structural analysis revealed that human DA41 cDNA consisted of 2,861 nucleotides in length and encoded a protein of 589 amino acids, with a predicted molecular mass of 62.4kDa. Human DA41 exhibited an 86% amino acid sequence identity to rat DA41, indicating the evolutionarily conserved structure and function of DA41. A database search for DA41-related protein(s) identified mouse PLIC-1, PLIC-2, frog XDRP1, and yeast DSK2. DA41 and each DA41-related protein contain a ubiquitin-like domain in their amino-terminal regions. DA41 was expressed ubiquitously in adult human tissues, with relatively higher levels in pituitary gland, adrenal gland, kidney, thymus, and placenta. Fluorescence in situ hybridization (FISH) revealed that DA41 was mapped to human chromosome 9q21.2-q21.3, a position overlapping the candidate tumor suppressor locus for bladder cancer.