DQX1 is a novel gene related to the RNA-dependent ATPases. The gene was classified as a member of the DEAD/H family on the basis of the conserved order and spacing of ten short protein motifs. The unique features of DQX1 include replacement of the signature DEAH motif with DEAQ and the absence of the helicase motif. We determined the coding sequences of human and mouse DQX1, which encode proteins of 717 and 718 amino acids with 84% amino acid sequence identity. The 3.2-kb Dqx1 transcript has highest expression in muscle and liver. DQX1 is located between AUP1 and HOX11L1 in a gene-dense region of human Chromosome (Chr) 2p13 and mouse Chr 6. Although DQX1 is within the nonrecombinant region for the mouse neuromuscular mutant mnd2, no difference in coding sequence, transcript length, or transcript abundance was observed between normal mice and mnd2 mutant mice. The ubiquitous expression of DQX1 and its close phylogenetic relationship to the yeast pre-mRNA processing (Prp) proteins suggest a role in cellular RNA metabolism.