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)

mid1 is required for the proper placement of the contractile actin ring for cytokinesis at a medial site overlying the nucleus. Here we find that mid1 protein (mid1p) shuttles between the nucleus and a cortical medial broad band during interphase and early mitosis. The position of this broad band, which overlies the nucleus, is linked to nuclear position even in cells with displaced or multiple nuclei. We identified and created mutations in an NLS and in two crm1-dependent NES sequences in mid1p. NES mutations caused mid1p accumulation in the nucleus and loss of function. An NLS mutations greatly reduced nuclear localization but did not perturb cytoplasmic localization or function. mid1p localization to the medial broad band was also not dependent on mid1p PH domain or microtubule and actin cytoskeletons. Overexpression of mid1p produced ectopic cell growth at this band during interphase and abnormal karmellae-like nuclear membrane structures. In plo1-1, mid1p formed a medial broad band but did not incorporate into a tight ring, suggesting that polo kinase plo1p is required for activation of mid1p function. Thus, the mid1p broad band defines a compartment at the medial cell surface, whose localization is linked to the position of the nucleus, and whose function may be to position the plane of cell division.
Mol Biol Cell 2000 Aug
PMID:Analysis of mid1p, a protein required for placement of the cell division site, reveals a link between the nucleus and the cell surface in fission yeast. 1093 Apr 68

PMCHL1 and PMCHL2 are two copies of the so-called variant melanin-concentrating hormone (MCH) gene that are located, respectively, on human chromosome 5p14 and 5q13 and that emerged recently during primate evolution. They correspond to a 5'-end truncated version of the MCH gene mapped on chromosome 12q23 and encoding a neuropeptide precursor. The gene organization and regulation of the expression of the variant MCH genes in the human brain are the central issues we investigated. First, the structure and fine chromosomal mapping of the 5p and 5q variant MCH genes were established. These revealed several point mutations and length variations of one CA/TA repeat which allow discrimination between each copy. Using a combination of RACE-PCR, RT-PCR, and sequencing analysis, we provided strong evidence for the expression of the PMCHL1 gene but not the PMCHL2 gene in the human fetal, newborn, and adult brains. Sense, potentially coding, RNAs, as well as noncoding antisense RNAs, were identified and displayed a region-specific expression in the human brain. Strikingly, sense unspliced RNAs of the PMCHL1 gene carried a novel open reading frame and may produce an NLS-containing protein of 8 kDa named VMCH-p8. These transcripts were translated in vitro and in transfected COS cells. Therefore, the PMCHL1 gene provides a unique example of the generation of a gene in the Hominoidae lineage which is specifically transcribed in the developing human brain and has the capacity to be translated into a putative novel protein.
Mol Biol Evol 2000 Nov
PMID:Structure and expression of the variant melanin-concentrating hormone genes: only PMCHL1 is transcribed in the developing human brain and encodes a putative protein. 1107 51

The bidirectional nucleocytoplasmic transport of macromolecules is mediated by the nuclear pore complex (NPC) which, in yeast, is composed of approximately 30 different proteins (nucleoporins). Pre-embedding immunogold-electron microscopy revealed that Nic96p, an essential yeast nucleoporin, is located about the cytoplasmic and the nuclear periphery of the central channel, and near or at the distal ring of the yeast NPC. Genetic approaches further implicated Nic96p in nuclear protein import. To more specifically explore the potential role of Nic96p in nuclear protein import, we performed a two-hybrid screen with NIC96 as the bait against a yeast genomic library to identify transport factors and/or nucleoporins involved in nuclear protein import interacting with Nic96p. By doing so, we identified the yeast nucleoporin Nup53p, which also exhibits multiple locations within the yeast NPC and colocalizes with Nic96p in all its locations. Whereas Nup53p is directly involved in NLS-mediated protein import by its interaction with the yeast nuclear import receptor Kap95p, it appears not to participate in NES-dependent nuclear export.
Mol Biol Cell 2000 Nov
PMID:The yeast nucleoporin Nup53p specifically interacts with Nic96p and is directly involved in nuclear protein import. 1107 14

The mammalian DNA methyltransferase Dnmt1 is responsible for the maintenance of the pattern of DNA methylation in vivo. It is a large multidomain enzyme comprising 1620 amino acid residues. We have purified and characterized individual domains of Dnmt1 (NLS-containing domain, NlsD, amino acid residues: 1-343; replication foci-directing domain, 350-609; Zn-binding domain (ZnD), 613-748; polybromo domain, 746-1110; and the catalytic domain (CatD), 1124-1620). CatD, ZnD and NlsD bind to DNA, demonstrating the existence of three independent DNA-binding sites in Dnmt1. CatD shows a preference for binding to hemimethylated CpG-sites; ZnD prefers methylated CpGs; and NlsD specifically binds to CpG-sites, but does not discriminate between unmethylated and methylated DNA. These results are not compatible with the suggestion that the target recognition domain of Dnmt1 resides in the N terminus of the enzyme. We show by protein-protein interaction assays that ZnD and CatD interact with each other. The isolated catalytic domain does not methylate DNA, neither alone nor in combination with other domains. Full-length Dnmt1 was purified from baculovirus-infected insect cells. Under the experimental conditions, Dnmt1 has a strong (50-fold) preference for hemimethylated DNA. Dnmt1 is stimulated to methylate unmodified CpG sites by the addition of fully methylated DNA. This effect is dependent on Zn, suggesting that binding of methylated DNA to ZnD triggers the allosteric activation of the catalytic center of Dnmt1. The allosteric activation model can explain kinetic data obtained by others. It suggests that Dnmt1 might be responsible for spreading of methylation, a process that is observed during aging and carcenogenesis but may be important for de novo methylation of DNA.
J Mol Biol 2001 Jun 22
PMID:The activity of the murine DNA methyltransferase Dnmt1 is controlled by interaction of the catalytic domain with the N-terminal part of the enzyme leading to an allosteric activation of the enzyme after binding to methylated DNA. 1139 88

SHP-1 protein tyrosine phosphatase is a critical regulator of signaling in hematopoietic cells as illustrated by the lethal hematopoietic disorders in SHP-1-deficient mice. We and others have shown in previous studies that SHP-1 regulates membrane receptor signaling: it binds via its N-terminal region SH2 domains to tyrosine phosphorylated membrane receptors to dephosphorylate key substrates in the receptor complexes. Here we demonstrate that the SHP-1 C-terminal region contains a bipartite NLS that mediates SHP-1 nuclear localization in response to cytokines. This NLS was located within amino acids 576-595 of the PTPase and, when fused by itself to EGFP, targeted the fluorescent protein into the nuclei of transiently transfected NIH3T3 fibroblasts and Bac1.2f5 macrophage cells. When positioned within SHP-1, the activity of the NSL was under tight regulation as indicated by the predominant cytoplasmic distribution of the EGFP/SHP-1 fusion protein in NIH3T3 transfectants and the exclusive cytoplasmic localization of the endogenous SHP-1 in hematopoietic cell line PBLC-1. Activation of the NLS in SHP-1 by IL-4 was demonstrated by increased nuclear localization of the EGFP/SHP-1 fusion protein in NIH3T3 transfectants and of the endogenous SHP-1 protein in PBCL-1 cells at 4, 6 and 8 h post-IL-4 stimulation. SHP-1 nuclear localization in PBCL-1 cells was also induced by IL-7 in a similar manner, suggesting it as a common event in cytokine signaling. In comparison to that of the wild-type phosphatase, an SHP-1 mutant lacking the NLS showed only approximately half of the activity in inhibiting proliferation of NIH3T3 transfectants. These results provide evidence of cytokine-regulated SHP-1 nuclear localization mediated by a bipartite NLS and suggest that SHP-1 regulates nuclear signaling in cell growth control.
Blood Cells Mol Dis
PMID:A bipartite NLS at the SHP-1 C-terminus mediates cytokine-induced SHP-1 nuclear localization in cell growth control. 1198 43

To facilitate nuclear delivery of biomolecules we describe the synthesis of a modular transporter bearing a cellular membrane transport peptide (pAntp) and, as a cargo, a 16-mer peptide nucleic acid (PNA) covalently linked to a nuclear localisation signal (NLS[SV40-T]). Transport peptide and PNA are connected via N-terminal activated cysteine to form cleavable disulphide bonds. Internalization and subsequent delivery of PNA to the nucleus was verified in living and fixed cells by confocal laser scanning microscopy (CLSM) and fluorescence correlation spectroscopy (FCS). Double-labelling experiments indicate the cytoplasmic cleavage of the two modules and the effective nuclear import of the chromophore-tagged cargo. A non-degradable linker between transport module and cargo as well as a construct without NLS did not enable nuclear PNA import under the described experimental conditions. FCS-measurements revealed that most of the PNAs delivered into the cytoplasm by the modular transporter are anchored or encapsulated, indicating that intracellular transport of these compounds is not governed by molecular diffusion. Our results clearly demonstrate efficient compartment-directed transport using a synthetic, non-toxic modular transporter in living cells.
J Mol Biol 2002 Apr 26
PMID:A biological transporter for the delivery of peptide nucleic acids (PNAs) to the nuclear compartment of living cells. 1205 33

IkappaBalpha inhibits transcription factor NF-kappaB activity by specific binding to NF-kappaB heterodimers composed of p65 and p50 subunits. It binds with slightly lower affinity to p65 homodimers and with significantly lower affinity to homodimers of p50. We have employed a structure-based mutagenesis approach coupled with protein-protein interaction assays to determine the source of this dimer selectivity exhibited by IkappaBalpha. Mutation of amino acid residues in IkappaBalpha that contact NF-kappaB only marginally affects complex binding affinity, indicating a lack of hot spots in NF-kappaB/IkappaBalpha complex formation. Conversion of the weak binding NF-kappaB p50 homodimer into a high affinity binding partner of IkappaBalpha requires transfer of both the NLS polypeptide and amino acid residues Asn202 and Ser203 from the NF-kappaB p65 subunit. Involvement of Asn202 and Ser203 in complex formation is surprising as these amino acid residues occupy solvent exposed positions at a distance of 20A from IkappaBalpha in the crystal structures. However, the same amino acid residue positions have been genetically isolated as determinants of binding specificity in a homologous system in Drosophila. X-ray crystallographic and solvent accessibility experiments suggest that these solvent-exposed amino acid residues contribute to NF-kappaB/IkappaBalpha complex formation by modulating the NF-kappaB p65 subunit NLS polypeptide.
J Mol Biol 2002 Dec 06
PMID:Solvent exposed non-contacting amino acids play a critical role in NF-kappaB/IkappaBalpha complex formation. 1246 May 63

The vertebrate nuclear pore complex, 30 times the size of a ribosome, assembles from a library of soluble subunits and two membrane proteins. Using immunodepletion of Xenopus nuclear reconstitution extracts, it has previously been possible to assemble nuclei lacking pore subunits tied to protein import, export, or mRNA export. However, these altered pores all still possessed the bulk of pore structure. Here, we immunodeplete a single subunit, the Nup107-160 complex, using antibodies to Nup85 and Nup133, two of its components. The resulting reconstituted nuclei are severely defective for NLS import and DNA replication. Strikingly, they show a profound defect for every tested nucleoporin. Even the integral membrane proteins POM121 and gp210 are absent or unorganized. Scanning electron microscopy reveals pore-free nuclei, while addback of the Nup107-160 complex restores functional pores. We conclude that the Nup107-160 complex is a pivotal determinant for vertebrate nuclear pore complex assembly.
Mol Cell 2003 Apr
PMID:Removal of a single pore subcomplex results in vertebrate nuclei devoid of nuclear pores. 1271 72

In order to better understand the role of nuclear localization of polyglutamine in the human CAG repeat disorders, gene targeting was used to add either nuclear localization (NLS) or nuclear export (NES) signals to versions of the mouse Hprt protein containing expanded polyglutamine (HprtQ150). The NLS increased levels of nuclear HprtQ150 protein in the mouse brain and hastened both the presentation of neuronal intranuclear inclusions (NIIs) and the onset of behavioral abnormalities. The NES reduced levels of nuclear HprtQ150 protein in mouse brain and delayed both the presentation of NIIs and the onset of behavioral abnormalities. Together these results indicate the nucleus is the primary site of toxicity in HprtQ150 mice. Furthermore, the signals did not alter the relative regional distribution of NIIs, suggesting that factors other than nuclear access dictate the regional specificity of NII formation in this mouse model.
Hum Mol Genet 2003 Jul 01
PMID:Nucleocytoplasmic transport signals affect the age at onset of abnormalities in knock-in mice expressing polyglutamine within an ectopic protein context. 1281 88

Pav-KLP is the Drosophila member of the MKLP1 family essential for cytokinesis. In the syncytial blastoderm embryo, GFP-Pav-KLP cyclically associates with astral, spindle, and midzone microtubules and also to actomyosin pseudocleavage furrows. As the embryo cellularizes, GFP-Pav-KLP also localizes to the leading edge of the furrows that form cells. In mononucleate cells, nuclear localization of GFP-Pav-KLP is mediated through NLS elements in its C-terminal domain. Mutants in these elements that delocalize Pav-KLP to the cytoplasm in interphase do not affect cell division. In mitotic cells, one population of wild-type GFP-Pav-KLP associates with the spindle and concentrates in the midzone at anaphase B. A second is at the cell cortex on mitotic entry and later concentrates in the region of the cleavage furrow. An ATP binding mutant does not localize to the cortex and spindle midzone but accumulates on spindle pole microtubules to which actin is recruited. This leads either to failure of the cleavage furrow to form or later defects in which daughter cells remain connected by a microtubule bridge. Together, this suggests Pav-KLP transports elements of the actomyosin cytoskeleton to plus ends of astral microtubules in the equatorial region of the cell to permit cleavage ring formation.
Mol Biol Cell 2003 Oct
PMID:Localization of Pavarotti-KLP in living Drosophila embryos suggests roles in reorganizing the cortical cytoskeleton during the mitotic cycle. 1451 16


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