Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expansion of a polyglutamine tract within ataxin-1 causes spinocerebellar ataxia type 1 (SCA1). In this study, we used the yeast two-hybrid system to identify an ataxin-1-interacting protein, A1Up. A1Up localized to the nucleus and cytoplasm of transfected COS-1 cells. In the nucleus, A1Up co-localized with mutant ataxin-1, further demonstrating that A1Up interacts with ataxin-1. Expression analyses demonstrated that A1U mRNA is widely expressed as an approximately 4.0 kb transcript and is present in Purkinje cells, the primary site of SCA1 cerebellar pathology. Sequence comparisons revealed that A1Up contains an N-terminal ubiquitin-like (UbL) region, placing it within a large family of similar proteins. In addition, A1Up has substantial homology to human Chap1/Dsk2, a protein that binds the ATPase domain of the HSP70-like Stch protein. These results suggest that A1Up may link ataxin-1 with the chaperone and ubiquitin-proteasome pathways. In addition, these data support the concept that ataxin-1 may function in the formation and regulation of multimeric protein complexes within the nucleus.
Hum Mol Genet 2000 Sep 22
PMID:Identification and characterization of an ataxin-1-interacting protein: A1Up, a ubiquitin-like nuclear protein. 1100 34

The product of rat gene 33 was identified as an ErbB-2-interacting protein in a two-hybrid screen employing the ErbB-2 juxtamembrane and kinase domains as bait. This interaction was reproduced in vitro with a glutathione S-transferase fusion protein spanning positions 282 to 395 of the 459-residue gene 33 protein. Activation of ErbB-2 catalytic function was required for ErbB-2-gene 33 physical interaction in living cells, whereas ErbB-2 autophosphorylation was dispensable. Expression of gene 33 protein was absent in growth-arrested NIH 3T3 fibroblasts but was induced within 60 to 90 min of serum stimulation or activation of the ErbB-2 kinase and decreased sharply upon entry into S phase. New differentiation factor stimulation of mitogen-deprived mammary epithelial cells also caused accumulation of gene 33 protein, which could be found in a complex with ErbB-2. Overexpression of gene 33 protein in mouse fibroblasts inhibited (i) cell proliferation driven by ErbB-2 but not by serum, (ii) cell transformation induced by ErbB-2 but not by Ras or Src, and (iii) sustained activation of ERK 1 and 2 by ErbB-2 but not by serum. The gene 33 protein may convey inhibitory signals downstream to ErbB-2 by virtue of its association with SH3-containing proteins, including GRB-2, which was found to associate with gene 33 protein in living cells. These data indicate that the gene 33 protein is a feedback inhibitor of ErbB-2 mitogenic function and a suppressor of ErbB-2 oncogenic activity. We propose that the gene 33 protein be renamed with the acronym RALT (receptor-associated late transducer).
Mol Cell Biol 2000 Oct
PMID:Inhibition of ErbB-2 mitogenic and transforming activity by RALT, a mitogen-induced signal transducer which binds to the ErbB-2 kinase domain. 1100 69

Using a two-hybrid screening with TOM1, a putative ubiquitin-ligase gene of Saccharomyces cerevisiae, we isolated KRR1, a homologue of human HRB2 (for human immunodeficiency virus type 1 Rev-binding protein 2). To characterize the gene function, we constructed temperature-sensitive krr1 mutants and isolated two multicopy suppressors. One suppressor is RPS14A, encoding a 40S ribosomal protein. The C-terminal-truncated rpS14p, which was reported to have diminished binding activity to 18S rRNA, failed to suppress the krr1 mutant. The other suppressor is a novel gene, KRI1 (for KRR1 interacting protein; YNL308c). KRI1 is essential for viability, and Kri1p is localized to the nucleolus. We constructed a galactose-dependent kri1 strain by placing KRI1 under control of the GAL1 promoter, so that expression of KRI1 was shut off when transferring the culture to glucose medium. Polysome and 40S ribosome fractions were severely decreased in the krr1 mutant and Kri1p-depleted cells. Pulse-chase analysis of newly synthesized rRNAs demonstrated that 18S rRNA is not produced in either mutant. However, wild-type levels of 25S rRNA are made in either mutant. Northern analysis revealed that the steady-state levels of 18S rRNA and 20S pre-rRNAs were reduced in both mutants. Precursors for 18S rRNA were detected but probably very unstable in both mutants. A myc-tagged Kri1p coimmunoprecipitated with a hemagglutinin-tagged Krr1p. Furthermore, the krr1 mutant protein was defective in its interaction with Kri1p. These data lead us to conclude that Krr1p physically and functionally interacts with Kri1p to form a complex which is required for 40S ribosome biogenesis in the nucleolus.
Mol Cell Biol 2000 Nov
PMID:Yeast Krr1p physically and functionally interacts with a novel essential Kri1p, and both proteins are required for 40S ribosome biogenesis in the nucleolus. 1102 67

p53 is an important mediator of the cellular stress response with roles in cell cycle control, DNA repair, and apoptosis. 53BP2, a p53-interacting protein, enhances p53 transactivation, impedes cell cycle progression, and promotes apoptosis through unknown mechanisms. We now demonstrate that endogenous 53BP2 levels increase following UV irradiation induced DNA damage in a p53-independent manner. In contrast, we found that the presence of a wild-type (but not mutant) p53 gene suppressed 53BP2 steady-state levels in cell lines with defined p53 genotypes. Likewise, expression of a tetracycline-regulated wild-type p53 cDNA in p53-null fibroblasts caused a reduction in 53BP2 protein levels. However, 53BP2 levels were not reduced if the tetracycline-regulated p53 cDNA was expressed after UV damage in these cells. This suggests that UV damage activates cellular factors that can relieve the p53-mediated suppression of 53BP2 protein. To address the physiologic significance of 53BP2 induction, we utilized stable cell lines with a ponasterone A-regulated 53BP2 cDNA. Conditional expression of 53BP2 cDNA lowered the apoptotic threshold and decreased clonogenic survival following UV irradiation. Conversely, attenuation of endogenous 53BP2 induction with an antisense oligonucleotide resulted in enhanced clonogenic survival following UV irradiation. These results demonstrate that 53BP2 is a DNA damage-inducible protein that promotes DNA damage-induced apoptosis. Furthermore, 53BP2 expression is highly regulated and involves both p53-dependent and p53-independent mechanisms. Our data provide new insight into 53BP2 function and open new avenues for investigation into the cellular response to genotoxic stress.
Mol Cell Biol 2000 Nov
PMID:Proapoptotic p53-interacting protein 53BP2 is induced by UV irradiation but suppressed by p53. 1102 72

Two W chromosome-linked cDNA clones, p5fm2 and p5fm3, were obtained from a subtracted (female minus male) cDNA library prepared from a mixture of undifferentiated gonads and mesonephroi of male or female 5-d (stages 26-28) chicken embryos. These two clones were demonstrated to be derived from the mRNA encoding an altered form of PKC inhibitor/interacting protein (PKCI), and its gene was named Wpkci. The Wpkci gene reiterated approximately 40 times tandemly and located at the nonheterochromatic end of the chicken W chromosome. The W linkage and the moderate reiteration of Wpkci were conserved widely in Carinatae birds. The chicken PKCI gene, chPKCI, was shown to be a single-copy gene located near the centromere on the long arm of the Z chromosome. Deduced amino acid sequences of Wpkci and chPKCI showed approximately 65% identity. In the deduced sequence of Wpkci, the HIT motif, which is essential for PKCI function, was absent, but the alpha-helix region, which was conserved among the PKCI family, and a unique Leu- and Arg-rich region, were present. Transcripts from both Wpkci and chPKCI genes were present at significantly higher levels in 3- to 6-d (stages 20-29) embryos. These transcripts were detected in several embryonic tissues, including undifferentiated left and right gonads. When the green fluorescent protein-fused form of Wpkci was expressed in male chicken embryonic fibroblast, it was located almost exclusively in the nucleus. A model is presented suggesting that Wpkci may be involved in triggering the differentiation of ovary by interfering with PKCI function or by exhibiting its unique function in the nuclei of early female embryos.
Mol Biol Cell 2000 Oct
PMID:Wpkci, encoding an altered form of PKCI, is conserved widely on the avian W chromosome and expressed in early female embryos: implication of its role in female sex determination. 1102 61

The human androgen receptor (hAR) is a ligand-dependent transcription factor responsible for the development of the male phenotype. The mechanism whereby nuclear translocation of the hAR is induced by its natural ligand 5alpha-dihydrotestosterone is a phenomenon not fully understood. The two-hybrid interaction trap assay has been used to isolate proteins that interact with the hAR in an attempt to identify molecules involved in hAR transactivation and movement. We have identified the actin-binding protein filamin, a 280-kDa component of the cytoskeleton, as an hAR interacting protein. This interaction is ligand independent but is enhanced in its presence. The functional significance of this interaction was analyzed using a cell line deficient in filamin via transient expression of a green fluorescent protein-hAR chimera. In filamin-deficient cells this revealed that hAR remained cytoplasmic even after prolonged exposure to synthetic ligand. Nuclear shuttling was restored when this cell line regained wild-type expression of filamin. These data suggest a novel role for filamin, implicating it as an important molecule in AR movement from the cytoplasm to the nucleus.
Mol Endocrinol 2000 Oct
PMID:Androgen receptor nuclear translocation is facilitated by the f-actin cross-linking protein filamin. 1104 77

Transient cotransfection in COS-7 cells, a standard approach to demonstrate coactivation, was used to study the coactivation properties of NuRIP183, a new nuclear receptor interacting protein of 183 kDa, isolated by a yeast two-hybrid screening. Transfection with a NuRIP183 expression construct strongly increased the ligand-dependent response of reporter constructs for several nuclear receptors when compared to transfection with the empty expression vector. A more detailed study, however, revealed major changes in the expression level of the nuclear receptors in cotransfection experiments, indicating that the observed changes in receptor activity were not due to coactivation but to differences in receptor concentration caused by interference from the cotransfected expression constructs with the expression of the receptor. Such interference, which is inversely related to the length of the insert, was observed, not only in COS-7 cells but also in CV-1 and MCF-7 cells, using different transfection techniques (FuGENE-6 and calcium phosphate) and different expression vectors (pSG5, pcDNA1.1 and pIRESneo). These data cast some doubt on coactivation of nuclear receptors based on similar cotransfection experiments without measurement of receptor concentration. Moreover, it is recommended to limit the amounts of (co)transfected expression plasmid and to avoid the use of empty expression plasmid as a control. Finally, one should be aware of similar misleading results in other experimental set-ups based on cotransfection.
Mol Cell Endocrinol 2000 Oct 25
PMID:Apparent coactivation due to interference of expression constructs with nuclear receptor expression. 1106 49

A recently reported new member of the Vav family proteins, Vav3 has been identified as a Ros receptor protein tyrosine kinase (RPTK) interacting protein by yeast two-hybrid screening. Northern analysis shows that Vav3 has a broad tissue expression profile that is distinct from those of Vav and Vav2. Two species of Vav3 transcripts, 3.4 and 5.4 kb, were detected with a differential expression pattern in various tissues. Transient expression of Vav in 293T and NIH 3T3 cells demonstrated that ligand stimulation of several RPTKs (epidermal growth factor receptor [EGFR], Ros, insulin receptor [IR], and insulin-like growth factor I receptor [IGFR]) led to tyrosine phosphorylation of Vav3 and its association with the receptors as well as their downstream signaling molecules, including Shc, Grb2, phospholipase C (PLC-gamma), and phosphatidylinositol 3 kinase. In vitro binding assays using glutathione S-transferase-fusion polypeptides containing the GTPase-binding domains of Rok-alpha, Pak, or Ack revealed that overexpression of Vav3 in NIH 3T3 cells resulted in the activation of Rac-1 and Cdc42 whereas a deletion mutant lacking the N-terminal calponin homology and acidic region domains activated RhoA and Rac-1 but lost the ability to activate Cdc42. Vav3 induced marked membrane ruffles and microspikes in NIH 3T3 cells, while the N-terminal truncation mutants of Vav3 significantly enhanced membrane ruffle formation but had a reduced ability to induce microspikes. Activation of IR further enhanced the ability of Vav3 to induce membrane ruffles, but IGFR activation specifically promoted Vav3-mediated microspike formation. N-terminal truncation of Vav3 activated its transforming potential, as measured by focus-formation assays. We conclude that Vav3 mediates RPTK signaling and regulates GTPase activity, its native and mutant forms are able to modulate cell morphology, and it has the potential to induce cell transformation.
Mol Cell Biol 2000 Dec
PMID:Vav3 mediates receptor protein tyrosine kinase signaling, regulates GTPase activity, modulates cell morphology, and induces cell transformation. 1109 73

We have found that coilin, the marker protein for Cajal bodies (coiled bodies, CBs), is a self-interacting protein, and we have mapped the domain responsible for this activity to the amino-terminus. Together with a nuclear localization signal, the self-interaction domain is necessary and sufficient for localization to CBs. Overexpression of various wild-type and mutant coilin constructs in HeLa cells results in disruption of both CBs and survival motor neurons (SMN) gems. Additionally, we have identified a cryptic nucleolar localization signal (NoLS), within the coilin protein, which may be exposed in specific coilin phospho-isoforms. The implications of these findings are discussed in light of the fact that other proteins known to localize within nuclear bodies (e. g., PML, SMN and Sam68) can also self-associate. Thus protein self-interaction appears to be a general feature of nuclear body marker proteins.
Mol Biol Cell 2000 Dec
PMID:Self-association of coilin reveals a common theme in nuclear body localization. 1110 15

The mouse disabled 2 (mDab2) gene is a mouse homologue of the Drosophila disabled gene and is alternatively spliced to form two isoforms, p96 and p67. Although p96 has been known to regulate the Ras-Sos G-protein signal transduction pathway by interacting with Grb2, little is known about the biological function of p67. Recent studies have shown that the expression of mDab2 is markedly up-regulated during the retinoic acid (RA)-induced differentiation of F9 cells, suggesting another role for mDab2 in cell differentiation [Cho, Lee and Park (1999) Mol. Cells 9, 179-184). In the present study, we first elucidated the biological function of p67 isoform of mDab2 and identified its binding partner. Unlike p96, p67 largely resides in RA-treated F9 cell nuclei. In this system, p67 interacts with mouse androgen-receptor interacting protein 3, termed the mDab2 interacting protein, which acts as a transcriptional co-regulator. By using a fusion protein with a heterologous DNA-binding domain (GAL4), we showed that p67 had an intrinsic transcriptional activation function. These results suggest that mDab2 p67 may function as a transcriptional co-factor for certain complexes of transcriptional regulatory elements involved in the RA-induced differentiation of F9 cells.
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PMID:p67 isoform of mouse disabled 2 protein acts as a transcriptional activator during the differentiation of F9 cells. 1110 69


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