Following immunoscreening, we have cloned and sequenced a human cDNA encoding a novel member of the expanding helicase family. The deduced protein, designated hZFH (human zinc-finger helicase), contains the seven domains conserved among the helicase superfamily II and four potential zinc-fingers motifs. In particular, hZFH shows significant similarity to some proteins of the Snf2-like family, known to act as transcriptional regulators for multiples genes. Furthermore, hZFH has 68.5% identity to a human Mi-2 autoantigen to which autoantibodies are produced by a subgroup of patients affected by dermatomyositis. Northern-blot analyses have revealed several hZFH mRNAs with quantitative differences in various human tissues. One alternative splice site of hZFH mRNA was demonstrated and others were predicted. We also report the chromosomal localization of gene hZFH to locus 17p13-17p12 by in situ hybridization. Thus, this novel gene appears as a candidate for several malignant and genetic diseases associated with this region of the genome. The combination of these features suggests that hZFH plays an important role in gene regulation.Keywords : helicase ; human; cDNA; autoimmunity; chromosomal localization.Helicases constitute a large family of enzymes endowed with tional activation of a large set of inducible genes [7, 8]. These factors are believed to enhance transcription by assisting on ATPase activity and involved in double-stranded DNA and RNA unwinding. Numerous processes of nucleic acid metabolism, in-gene-specific activators in relieving repression, probably via an alteration of the chromatin structure [6, 9, 10]. cluding DNA replication, DNA repair, transcription, RNA splicing and translation require DNA and/or RNA helicases [1Ϫ3].Snf/Swi homologs have now been identified in Drosophila, mouse and human, suggesting a conserved role throughout euDespite the diversity of their physiological functions and the wide range of organisms in which they have been found, pro-karyotes in transcriptional activation. The human homolog, called hBRM, is 56% identical to brahma (also called brm), a nounced sequence conservation was maintained in helicase families. On the basis of different sequence signatures, the members regulator of homeotic genes in Drosophila [11], and 33% identical to yeast Snf2. hBRM was shown to be a strong activator of this protein family are subdivided into superfamilies I, II and III [4, 5]. Each protein of superfamilies I and II contains seven of transcription when tethered to DNA through fusion with a specific DNA-binding domain [12]. Moreover, hBRM (also highly conserved motifs (I, Ia, IIϪVI) termed helicase domains, clustered in a region of 200Ϫ700 amino acids. The similarity known as hSNF2A) and a strikingly related (75% identity) protein, BRG1 (also known as hSNF2β), can function as two tranin the structure and arrangement of these motifs suggests that superfamilies I and II have evolved from a common ances-scriptional coactivators cooperating with the estrogen, the glucocorticoid and the retin...