A conserved WD40 protein binds the Cajal body localization signal of scaRNP particles
- Mol Cell. 2009 Apr 10;34(1):47-57. doi: 10.1016/j.molcel.2009.02.020.
- 1. Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06536, USA.
Small Cajal body (CB)-specific RNPs (scaRNPs) function in posttranscriptional modification of small nuclear (sn)RNAs. An RNA element, the CAB box, facilitates CB localization of H/ACA scaRNPs. Using a related element in Drosophila C/D scaRNAs, we purified a fly WD40 repeat protein that UV crosslinks to RNA in a C/D CAB box-dependent manner and associates with C/D and mixed domain C/D-H/ACA scaRNAs. Its human homolog, WDR79, associates with C/D, H/ACA, and mixed domain scaRNAs, as well as with Telomerase RNA. WDR79's binding to human H/ACA and mixed domain scaRNAs is CAB box dependent, and its association with mixed domain RNAs also requires the ACA motif, arguing for additional interactions of WDR79 with H/ACA core proteins. We demonstrate a requirement for WDR79 binding in the CB localization of a scaRNA. This and Other recent reports establish WDR79 as a central player in the localization and processing of nuclear RNPs.