Xenopusinterspersed RNA families, Ocr and XR, bind DNA-binding proteins

Abstract

SummaryInterspersed RNA makes up two-thirds of cytoplasmic polyadenylated RNA inXenopusand sea urchin eggs.Although it has no known function, previous work has suggested that at least one family of interspersed RNA, XR, bindsXenopusoocyte proteins, and can influence the rate of translation. We have used twoXenopusrepeat families, Ocr and XR, to explore their protein binding abilities. Ocr RNA binds the same pattern of highly abundant oocyte proteins that XR RNA binds, which are believed to be messenger ribonucleoprotein (mRNP) particle proteins. In addition, we show that Ocr RNA binds the Oct-60 protein, a member of the POU-domain family of transcription factors found inXenopusoocytes. Using a 32 base pair sequence from the XR repeat in a DNA affinity column two proteins were isolated, 66KDa and 92KDa, that together form a complex with XR DNA. One of these proteins (92KDa) also binds XR RNA. We suggest that the role of at least a subset of interspersed RNAs in development may be to bind, and sequester in the cytoplasm, DNA-binding proteins until the end of oogenesis