title: Characterization of the sequences encoding for Xenopus laevis box C/D snoRNP Nop56 protein.
abstract: Nop56p was initially identified in yeast as the third common component of the ribonucleoprotein particles (snoRNPs) assembled on box C/D small nucleolar RNAs (snoRNAs). Thereafter, the characterization of Nop56p homologs in Archaea and in several eukaryotes pointed to the highly conserved structure of this factor. Studies in yeast indicate that Nop56 is not required for the stability of box C/D snoRNAs. Through the isolation of a Xenopus laevis Nop56 cDNA clone, we have been able to characterize the X. laevis Nop56 protein (XNop56p). We showed that it is a common component of X. laevis box C/D snoRNPs and that it displays the same electrophoretic mobility of p62 protein that we previously characterized as a box C/D snoRNP component, not essential for snoRNA stability in X. laevis. Mapping the 5' end of X. laevis Nop56 transcript indicates that it starts with a pyrimidine tract and the analysis of genomic clones revealed a snoRNA encoded in one of NOP56 introns. Although these two characteristics could suggest that XNOP56 is a TOP gene, it is not translationally controlled in a growth-dependent manner.
authors.affiliation: Istituto Pasteur Fondazione Cenci-Bolognetti, Dipartimento di Genetica e Biologia Molecolare, Università La Sapienza, Rome, Italy.
authors.forename: Fabiana
authors.initials: F
authors.lastname: Renzi
authors.forename: Daniela
authors.initials: D
authors.lastname: Filippini
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Loreni
authors.forename: Irene
authors.initials: I
authors.lastname: Bozzoni
authors.forename: Elisa
authors.initials: E
authors.lastname: Caffarelli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D020537:RNA, Small Nucleolar / Q000276:immunology / Q000378:metabolism; D016601:RNA-Binding Proteins; D020718:Ribonucleoproteins, Small Nucleolar / Q000235:genetics* / Q000276:immunology; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000235:genetics*
chemical_list: D000906:Antibodies; C430407:NOP56 protein, S cerevisiae; C486600:NOP56 protein, human; C486598:Nop56 protein, Xenopus; D009687:Nuclear Proteins; D020537:RNA, Small Nucleolar; D016601:RNA-Binding Proteins; D020718:Ribonucleoproteins, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; D029867:Xenopus Proteins