title: The essential Drosophila ATP-binding cassette domain protein, pixie, binds the 40 S ribosome in an ATP-dependent manner and is required for translation initiation.
abstract: The Drosophila gene, pixie, is an essential gene required for normal growth and translation. Pixie is the fly ortholog of human RLI, which was first identified as an RNase L inhibitor, and yeast Rli1p, which has recently been shown to play a role in translation initiation and ribosome biogenesis. These proteins are all soluble ATP-binding cassette proteins with two N-terminal iron-sulfur clusters. Here we demonstrate that Pixie can be isolated from cells in complex with eukaryotic translation initiation factor 3 and ribosomal proteins of the small subunit. In addition, our analysis of polysome profiles reveals that double-stranded RNA interference-mediated depletion of Pixie results in an increase in empty 80 S ribosomes and a corresponding decrease in polysomes. Thus Pixie is required for normal levels of translation initiation. We also find that Pixie associates with the 40 S subunit on sucrose density gradients in an ATP-dependent manner. Our observations are consistent with Pixie playing a catalytic role in the assembly of complexes required for translation initiation. Thus, the function of this soluble ATP-binding cassette domain protein family in translation initiation has been conserved from yeast through to higher eukaryotes.
authors: Growth Regulation Laboratory, Cancer Research UK London Research Institute, P O Box 123, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom.
authors: Ditte S
authors: DS
authors: Andersen
authors: Sally J
authors: SJ
authors: Leevers
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D039621:Eukaryotic Initiation Factor-3 / Q000378:metabolism*; D006801:Humans; D010442:Peptide Chain Initiation, Translational / Q000502:physiology*; D011132:Polyribosomes / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology
chemical_list: D018528:ATP-Binding Cassette Transporters; D029721:Drosophila Proteins; D039621:Eukaryotic Initiation Factor-3; C521107:pix protein, drosophila; D000255:Adenosine Triphosphate