The developmentally-regulated Drosophila gene rox8 encodes an RRM-type RNA binding protein structurally related to human TIA-1-type nucleolysins

Abstract

We report the molecular analysis of a novel Drosophila melanogaster gene, rox8, isolated in a PCR-based screen for sequences encoding RRM-type RNA-bindlng polypeptides. The rox8 gene is predicted to encode a 50-kilodalton protein displaying extensive amino acid sequence similarities (46% overall Identity; 57 to 60% similarity) to the two recently described human TIA-1-type nucleolysins. These cytolytic granule associated proteins, which bind polyadenylated sequences in vitro and trigger DNA fragmentation in permeabllized target cells, are suspected to participate in the apoptotlc cell death pathway induced by T-lymphocytes and natural killer cells. The structural relatedness of the three proteins includes three tandemly-repeated consensus RNA-recognltlon motifs at the N-termlnal end and a putative membrane targeting signal at the C-terminal end. rox8 cytologically maps to 95D5-9 on the right arm of the third chromosome. Two rox8 transcripts of 3 and 3.3 kb in length, respectively, result from a developmentally modulated alternative usage of different polyadenylatlon sites and are differentially accumulated throughout the fly life cycle. Molecular characterization of rox8 represents the first step in a genetic analysis of the potential roles of a TIA-1-related protein in RNA metabolism and/or programmed cell death in Drosophila. © 1993 Oxford University Press.