Nuclear and nucleolar targeting of human ribosomal protein S6.

Schmidt, Christiane Mello; Lipsius, Edgar; Kruppa, Joachim

doi:10.1091/mbc.6.12.1875

Cited by 59 publications

(52 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…What is clear from a comparison of the aa sequences of the two nucleolar address-contributing regions of protein N038 (B23) is that the sequences under question do not comprise any possible NLS-like element, as reported for the putative nucleolar-addressing sequences in viral proteins of HIV (Rev and Tat) and human T-cell leukemia virus (Rex; for references, see INTRODUCTION), the human nucleolar protein p120 (Valdez et al, 1994), and the ribosomal proteins L31 (Quaye et al, 1996) and S6 (Schmidt et al, 1995). Moreover, the regions containing the nucleolar address segment of protein N038 do not reveal any clustering of basic aa or any known nucleic acid-binding motif as reported for other nucleolar proteins such as transcription factor mUBF (Maeda et al, 1992), nucleolin (Creancier et al, 1993;Megmer and Dreyer, 1993;Schmidt-Zachman and Nigg, 1993) and yeast nucleolar proteins NSR1 (Yan and Melese, 1993) and GAR1 (Girard et al, 1994).…”

Section: Subnucleolar Localization Of the Chimericmentioning

confidence: 89%

Topogenesis of a nucleolar protein: determination of molecular segments directing nucleolar association.

Zirwes

Kouzmenko

Peters

et al. 1997

MBoC

View full text Add to dashboard Cite

To identify the element(s) in nucleolar proteins which determine nucleolus-specific topogenesis, we have used different kinds of cDNA constructs encoding various chimeric combinations of mutants of the constitutive nucleolar protein N038 (B23): 1) with an amino terminally placed short "myc tag"; 2) with two different carboxyl terminally attached large a-helical coiled coil structures, the lamin A rod domain or the rod domain of vimentin; 3) with the sequence-related nucleoplasmic histone-binding protein nucleoplasmin; and 4) with the soluble cytoplasmic protein pyruvate kinase. To avoid the problem of formation of complexes with endogenous wild-type (wt) molecules and "piggyback" localization, special care was taken to secure that the mutants and chimeras used did not oligomerize as is typical of protein N038 (B23). Using microinjection and transfection of cultured cells, we found that the segment comprising the amino-terminal 123 amino acids (aa) alone was sufficient to effect nucleolar accumulation of the construct molecules, including the chimeras with the entire rod domains of lamin A and vimentin. However, when the amino-terminal 109 aa were deleted, the molecules still associated with the nucleolus. The results of further deletion experiments and of domain swaps with nucleoplasmin all point to the topogenic importance of two independent molecular regions located at both the amino-and carboxyl-terminal end. Our definition of dominant elements determining the nucleolar localization of protein N038 (B23) as well as of diverse nonnucleolar proteins will help to identify its local binding partner(s) and functions, the construction of probes examining other proteins or sequence elements within the nucleolar microenvironment, and the generation of cells with an altered nuclear architecture.

show abstract

Section: Subnucleolar Localization Of the Chimericmentioning

confidence: 89%

Topogenesis of a nucleolar protein: determination of molecular segments directing nucleolar association.

Zirwes

Kouzmenko

Peters

et al. 1997

MBoC

View full text Add to dashboard Cite

show abstract

“…By looking for sequential similarities between the hLa-NoLS described here and other published sequences mediating nucleolar localization of different human proteins (45)(46)(47)(48)(49)(50)(51)(75)(76)(77)(78), we aligned those sequences with the hLa-NoLS (Fig. 4C).…”

Section: Discussionmentioning

confidence: 99%

Nuclear Trafficking of La Protein Depends on a Newly Identified Nucleolar Localization Signal and the Ability to Bind RNA

Horke

Reumann

Schweizer

et al. 2004

Journal of Biological Chemistry

View full text Add to dashboard Cite

Here we provide evidence for an interaction-dependent subnuclear trafficking of the human La (hLa) protein, known as transient interaction partner of a variety of RNAs. Among these, precursor transcripts of certain RNAs are located in the nucleoplasm or nucleolus. Here we examined which functional domains of hLa are involved in its nuclear trafficking. By using green fluorescent-hLa fusion proteins, we discovered a nucleolar localization signal and demonstrated its functionality in a heterologous context. In addition, we revealed that the RRM2 motif of hLa is essential both for its RNA binding competence in vitro and in vivo and its exit from the nucleolus. Our data imply that hLa traffics between different subnuclear compartments, which depend decisively on a functional nucleolar localization signal as well as on RNA binding. Directed trafficking of hLa is fully consistent with its function in the maturation of precursor RNAs located in different subnuclear compartments.The human La protein (hLa) 1 is a 47-kDa phosphoprotein predominantly localized in the nucleus. It was first discovered as an autoantigen recognized by antibodies present in the sera of patients suffering from systemic lupus erythematosus and Sjogren's syndrome (1, 2). The La protein is a member of a large group of RNA-binding proteins containing RNA recognition motifs (RRMs) (3-7) and interacts with a variety of small RNAs (for reviews see Refs. 8 -10). The La protein is implicated in several aspects of the RNA metabolism, including processing of precursors of tRNAs, U3 snoRNA, U1 RNA, U6 snRNA (11)(12)(13)(14)(15)(16)(17)(18)(19)(20), and stabilization of viral (21-23) as well as cellular RNAs (24). In the cytoplasm, La has been implicated in the translational control of viral (25-27) and cellular RNAs (28 -30).The human La protein contains a nuclear localization sequence at the very C-terminal end, and the staining for endogenous La as well as the distribution of GFP-tagged La reveal a predominantly diffuse nuclear staining, although this may appear different under certain conditions or treatments (31-33). Subcellular distribution of human and yeast La was assumed to be independent of phosphorylation (34, 35); however, recent studies (36, 37) revealed that phosphorylation at Ser-366 may well influence subcellular localization of La. A regulated, nonhomogeneous nuclear distribution of La may also be predicted from the distinct nuclear distribution of its various RNA interaction partners. For instance, pre-tRNAs are most likely synthesized in the nucleoplasm (38) but are processed, at least in part, in the nucleolus (39, 40), whereas in yeast the La-associated precursor of U3 snoRNA is probably processed in the nucleolar body and nucleolus (20). Nevertheless, interactions with precursor RNAs in different nuclear compartments implicate a highly dynamic and regulated nuclear distribution of La. Although a nucleolar localization of La has been reported (for review see Ref. 9), the hLa protein was not identified among the recently resolved protein ...

show abstract

“…Also, investigations of the other human ribosomal proteins revealed such features in their nucleolar targeting. In S6, portions of approximately 60 residues were shown as minimum continuous fragments to confer nuclear/nucleolar targeting, in which two independent basic amino acid stretches seemed to cooperate (Schmidt et al, 1995). In the case of L7a, the amino-terminal 100 residue fragment was necessary and sucient for the nuclear/nucleolar targeting, which was also enabled by the combination of 17 residue amino terminal peptide and another portion (residue number 52 ± 100) in the fragment (Russo et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

“…Indeed, all the recent similar works on human ribosomal proteins have employed either epitopetagging systems (Moreland et al, 1985;Michael and Dreyfuss, 1996;Martin-Nieto and Roufa, 1997) or even b-galactosidase fusions (Schmidt et al, 1995;Russo et al, 1997). Following the more well-accepted former strategy, an RPS25 expression vector, pcFL-RPS25, was designed ( Figure 1a).…”

Section: Expression and Characterization Of An Epitope-tagged Rps25mentioning

confidence: 99%

“…The functional signi®cance of the nucleolar localization of these proteins is still controversial, although a possible role of the nucleolus as a storage site for the proteins is suggested in the case of the HIV-1 Rev protein (Kubota et al, 1996), which shuttles between the cytoplasm and the nucleus, to enable the nuclear export of unspliced viral mRNAs (Malim et al, 1989a,b;Fischer et al, 1994;Kalland et al, 1994;Meyer and Malim, 1994;Richard et al, 1994). Despite its evident functional signi®cance as a pre-event of ribosomal assembly, nucleolar targeting of human ribosomal proteins has been characterized in only a few members, S6, S14 and L7a (Schmidt et al, 1995;Martin-Nieto and Roufa, 1997;Russo et al, 1997). Therefore, further analyses of the nucleolar targeting of other ribosomal proteins seem to be required to gain insights into not only ribosomal biogenesis, but also the role of the nucleolar localization of such RNAbinding transactivators.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Nuclear and nucleolar targeting of human ribosomal protein S25: Common features shared with HIV-1 regulatory proteins

1999

View full text Add to dashboard Cite

The nuclear and nucleolar targeting properties of human ribosomal protein S25 (RPS25) were analysed by the expression of epitope-tagged RPS25 cDNAs in Cos-1 cells. The tagged RPS25 was localized to the cell nucleus, with a strong predominance in the nucleolus. At the amino terminus of RPS25, two stretches of highly basic residues juxtapose. This con®guration shares common features with the nucleolar targeting signals (NOS) of lentiviral RNA-binding transactivators, including human immunode®ciency viruses' (HIV) Rev proteins. Deletion and site-directed mutational analyses demonstrated that the ®rst NOS-like stretch is dispensable for both nuclear and nucleolar localization of RPS25, and that the nuclear targeting signal is located within the second NOS-like stretch. It has also been suggested that a set of continuous basic residues and the total number of basic residues should be required for nucleolar targeting. Signal-mediated nuclear/nucleolar targeting was further characterized by the construction and expression of a variety of chimeric constructs, utilizing three dierent backbones with RPS25 cDNA fragments. Immuno¯uorescence analyses demonstrated a 17 residue peptide of RPS25 as a potential nuclear/ nucleolar targeting signal. The identi®ed peptide signal may belong to a putative subclass of NOS, characterized by compact structure, together with lentiviral RNAbinding transactivators.

show abstract

Nuclear and nucleolar targeting of human ribosomal protein S6.

Cited by 59 publications

References 74 publications

Topogenesis of a nucleolar protein: determination of molecular segments directing nucleolar association.

Topogenesis of a nucleolar protein: determination of molecular segments directing nucleolar association.

Nuclear Trafficking of La Protein Depends on a Newly Identified Nucleolar Localization Signal and the Ability to Bind RNA

Nuclear and nucleolar targeting of human ribosomal protein S25: Common features shared with HIV-1 regulatory proteins

Contact Info

Product

Resources

About