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Mol. Cell. Biol., 01 1998, 488-498, Vol 18, No. 1
H Pluk, J Soffner, R Luhrmann and WJ van Venrooij
The eukaryotic nucleolus contains a large number of small RNA molecules
(snoRNAs) which, in the form of small nucleolar ribonucleoprotein complexes
(snoRNPs), are involved in the processing and modification of pre-rRNA. The
most abundant and one of the best-conserved snoRNAs is the U3 RNA. So far,
only one human U3 snoRNA-associated protein, fibrillarin, has been
characterized. Previously, the U3 snoRNPwas purified from CHO cells, and
three proteins of 15, 50, and 55 kDa were found to copurify with the U3
snoRNA (B. Lubben, C. Marshallsay, N. Rottmann, and R. Luhrmann, Nucleic
Acids Res. 21:5377-5385, 1993). Here we report the cDNA cloning and
characterization of the human U3 snoRNP- associated 55-kDa protein. The
isolated cDNA codes for a novel nucleolar protein which is specifically
associated with the U3 snoRNA. This protein, referred to as hU3-55k, is the
first characterized U3 snoRNP-specific protein from humans. hU3-55k is a
new member of the family of WD-40 repeat proteins and is conserved
throughout evolution. It appears that the C-terminal end of hU3-55k is
required for nucleolar localization and U3 snoRNA binding.
Copyright © 1998, American Society for Microbiology
cDNA cloning and characterization of the human U3 small nucleolar ribonucleoprotein complex-associated 55-kilodalton protein
Department of Biochemistry, University of Nijmegen, The Netherlands.
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