Separable roles in vivo for the two RNA binding domains of Drosophila A1-hnRNP homolog.
We analyzed the roles of the three domains of a Drosophila hnRNP A1 homolog by expression of wild-type and mutant versions of HRB87F/hrp36 in Drosophila melanogaster. HRB87F/hrp36 is one of two Drosophila proteins that is most similar to mammalian A1 hnRNP, and like A1, consists of two copies of the RNA-binding domain (RBD) motif followed by a glycine-rich domain (GRD). The role of the domains in nuclear localization and RNA binding to polytene chromosomal sites was determined. RBD-1 and the GRD were largely responsible for both the cellular location of the protein and for the typical chromosomal distribution pattern of the protein at sites of PolII transcription. RBD-1 also provided a role in the exon-skipping activity of the protein that was not provided by RBD-2. On the other hand, RBD-2 and the GRD were responsible for the very limited chromosomal distribution pattern seen upon heat shock, when HRB87F/hrp36 is sequestered at heat-shock puff 93D, which encodes a long nucleus-restricted RNA. Thus, these studies indicate that the two RBDs function independently of each other but in concert with the GRD. In addition, the self-association property of the GRD was strikingly evident in these overexpressed proteins.
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Department of Microbiology, University of Virginia, Charlottesville 22908, USA.
Sikes
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Beyer
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D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D017931:DNA Primers; D004331:Drosophila melanogaster / Q000235:genetics* / Q000254:growth & development; D005091:Exons; D005998:Glycine / Q000378:metabolism; D018869:Heat-Shock Response; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D005998:Glycine