A second maternally expressed Drosophila gene encodes a putative RNA helicase of the "DEAD box" family.

Abstract

Recently, a family of proteins containing the conserved motif Asp-Glu-Ala-Asp, the "DEAD box" proteins, has been identified. This family is typified by the eukaryotic translation initiation factor eIF4A, and its members are believed to share the functional property of ATP-dependent RNA unwinding. One of the previously identified members of this family (vasa) is the product of a maternally expressed gene from DrosophUa melanogaster that is known to play a role in the formation of the embryonic body plan. We report here the isolation of a Drosophila gene that has an mRNA expression pattern somewhat similar to that of vasa and also encodes a DEAD box protein. We have termed this gene ME3JB to reflect its maternal (ovarian germ-line) expression and its location within the 31B chromosome region. Comparisons with the other members of this family reveal that although ME31B is most like the protein Tifl/Tif2, which probably represents the Saccharomyces cerevisiae version of eIF4A, it is unlikely that ME31B represents the Drosophila eIF4A protein per se. A search for mutations in the ME3JB gene has established that the P element which causes the female-sterile mutation flipper lies in the 3' flank of the ME3JB gene.Recently a family of proteins that function as ATP-dependent RNA helicases has been identified (1).These proteins share a domain of about 370 amino acids in which a series of highly conserved motifs are arranged in identical order and with very similar spacing. Two of these conserved sequences represent specialized versions of the A and B motifs previously recognized in other ATP-binding proteins (2,3). The four-amino-acid sequence Asp-Glu-Ala-Asp (DEAD) is part ofthe specialized version ofthe B motif. These "DEAD box" proteins derive from organisms across all evolutionary orders (Escherichia coli to mouse), and for some of them, genetic and molecular studies have provided indications as to their functions in vivo (4-7). Thus this family of proteins appears to be involved in a wide range of intracellular events in which alteration of RNA secondary structure must play a critical role. These include formation of the initiation complex for mRNA translation, mRNA splicing, and ribosome biosynthesis. Functionally, the eukaryotic translation initiation factor eIF4A, which is the archetypal member of the family, is the one best understood at the molecular level (8-10).

DjCBC‐1, a conserved DEAD box RNA helicase of the RCK/p54/Me31B family, is a component of RNA‐protein complexes in planarian stem cells and neurons

“…The expression of Djcbc-1 orthologs in somatic cells and neurons has been reported in other animals. In many cases, these ortholog proteins are localized in granular structures, such as p-bodies or stress granules, and repress the translation or promote the degradation of mRNA (De Valoir et al, 1991;Navarro et al, 2001;Cougot et al, 2004;Wilczynska et al, 2005;Barbee et al, 2006). It is possible that in planarians, DjCBC-1 may have a role in mRNA regulation in neurons, like its orthologs in other animals.…”

DDX1 is required for testicular tumorigenesis, partially through the transcriptional activation of 12p stem cell genes

“…DDX1 is a putative, ATP-dependent RNA helicase belonging to the DEAD-box family that is characterized by its Asp-Glu-Ala-Asp (DEAD) motif (Linder et al, 1989). More than 40 DEAD-box proteins have been identified in a variety of species from bacteria to human (de Valoir et al, 1991;Linder, 2006). In general, DEADbox protein family members are involved in RNA unwinding processes, such as translational initiation, mRNA splicing and ribosome assembly (Rocak and Linder, 2004).…”

Cloning, expression and localization of an RNA helicase gene from a human lymphoid cell line with chromosomal breakpoint 11q23.3

“…The second group includes proteins involved in pre-mRNA splicing (e.g., PRP5 and PRP28) [7,8], pre-rRNA splicing (SPB4) [9], and mitochondrial RNA splicing (MSS1 16) [10] in yeast. The third group of RNA helicases includes genes abundantly or specifically expressed in germline cells (vasa in male and female germline of Drosophila [11], ME31B in female germ cells of Drosophila [12], and PL1O in male germline of mouse [13]). In this work, we describe a human p54 gene with structural features very closely resembling the oocyte-specific ME31B gene of Drosophila, but having widespread and abundant transcriptional expression in human adult tissues.…”