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)

The 20S RNA of Saccharomyces cerevisiae is a single-stranded, circular RNA virus. A previous study suggested that this RNA is part of a 32S ribonucleoprotein particle, being associated with multiple copies of a 23-kilodalton protein. We show here that this protein is, in fact, the chromosome-encoded heat shock protein Hsp26. Furthermore, it is apparently not associated with 20S RNA and plays no obvious role in the life cycle of the virus.
Mol Cell Biol 1991 May
PMID:Is 20S RNA naked? 201 85

A low molecular weight heat shock protein which localizes to chloroplasts has been identified in several plant species. This protein belongs to a eukaryotic superfamily of small HSPs, all of which contain a conserved carboxyl-terminal domain. To investigate further the structure of this HSP, we isolated and sequenced cDNA clones for the chloroplast LMW HSPs from Petunia hybrida and Arabidopsis thaliana. The cloning of chloroplast HSPs from these two species enabled us to compare the amino acid sequences of this protein from plant species (petunia, Arabidopsis, pea, soybean and maize) that represent evolutionarily divergent taxonomic subclasses. Three conserved regions were identified, which are designated as regions I, II and III. Regions I and II are also shared by cytoplasmic LMW HSPs and therefore are likely to have functional roles common to all eukaryotic LMW HSPs. In contrast, consensus region III is not found in other LMW HSPs. Secondary structure analysis predicts that this region forms an amphipathic alpha-helix with high conservation of methionine residues on the hydrophobic face and 100% conservation of residues on the hydrophilic face. This structure is similar to three helices, termed "methionine bristles", which are found in a methionine-rich domain of a 54 kDa protein component of signal recognition particle (SRP54). The conservation of regions I and II among LMW cytoplasmic and chloroplast HSPs suggests that these HSPs perform related functions in different cellular compartments. However, identification of the methionine bristle domain suggests that chloroplast HSPs also have unique functions or substrates within the special environment of the chloroplast or other plastids.
Mol Gen Genet 1991 May
PMID:Analysis of conserved domains identifies a unique structural feature of a chloroplast heat shock protein. 188 17

Mouse glucocorticoid receptors (GR) that are over-expressed in Chinese hamster ovary (CHO) cells behave like progesterone receptors, in that the unliganded receptor localizes to the nucleus where it resides in a loosely bound docking complex, probably in association with the 90-kDa heat shock protein (hsp90) and hsp70. In this paper we examine the localization of the overexpressed GR within the CHO cell nucleus by confocal microscopy. In hormone-free cells the receptor distributes in a mottled pattern throughout all planes of the nucleus. The receptor is not present in nucleoli and shows no preferential localization in the periphery vs. the center of the nucleus. The mottled distribution in each plane of the nucleus demonstrates clearly that there are regions that do not contain receptor; thus, the distribution of the GR is not random. When triamcinolone acetonide is added to the CHO cells, there is no detectable change in receptor distribution. Overexpressed receptors that have either no hormone-binding activity or no DNA-binding activity because of point mutations localize in the same mottled pattern as the wild-type receptor. These observations are consistent with the proposal that the overexpressed GR can enter the nucleus in its unliganded state and proceed to loci distributed throughout the nucleus, where it is retained in an inactive docking complex until the binding of hormone triggers its progression to high affinity sites where the primary events in transcriptional activation occur. As there is no detectable change in localization with the addition of ligand, we suggest that the docking complex may be located very near or possibly at the site where the primary events in transcriptional activation occur.
Mol Endocrinol 1991 Feb
PMID:Demonstration by confocal microscopy that unliganded overexpressed glucocorticoid receptors are distributed in a nonrandom manner throughout all planes of the nucleus. 203 43

We report the isolation and characterization of a cDNA clone encoding HSP47, a transformation-sensitive heat shock protein that binds to collagen. A cDNA library was prepared from total RNA isolated from heat-shocked chicken embryo fibroblasts and screened by using oligonucleotide mixtures prepared on the basis of the N-terminal amino acid sequence of biochemically purified HSP47. The cDNA insert contained 3,278 bp, which encoded a 15-amino-acid signal peptide and a mature protein coding region consisting of 390 amino acid residues; it also included part of the 5' noncoding region and a long 3' noncoding region. The deduced amino acid sequence revealed an RDEL sequence at the C terminus, which is a variant of the KDEL retention signal for retention of proteins in the endoplasmic reticulum. Northern (RNA) blot analyses and nuclear run-on assays established that the induction of HSP47 by heat shock and its suppression after transformation of chicken embryo fibroblasts by Rous sarcoma virus are regulated at the transcriptional level. A homology search revealed that this protein belongs to the serpin family, the superfamily of plasma serine protease inhibitors. Although structurally homologous to the serpins, HSP47 lacks the active site thought to be essential for the inhibition of proteases and does not appear to bind to intracellular proteases. HSP47 is the first heat shock protein found to be a member of the serpin superfamily. Conversely, it is the first serpin family member that is not secreted from cells, which could be explained by acquisition of the RDEL retention signal during evolution.
Mol Cell Biol 1991 Aug
PMID:HSP47: a tissue-specific, transformation-sensitive, collagen-binding heat shock protein of chicken embryo fibroblasts. 207 6

hsp26, the small heat shock protein of Saccharomyces cerevisiae, accumulates in response to heat and other types of stress. It also accumulates during the normal course of development, as cells enter stationary phase growth or begin to sporulate (S. Kurtz, J. Rossi, L. Petko, and S. Lindquist, Science 231:1154-1157, 1986). Analysis of deletion and insertion mutations demonstrated that transcriptional control plays a critical role in regulating HSP26 expression. The HSP26 promoter was found to be complex and appears to contain repressing elements as well as activating elements. Several upstream deletion mutations resulted in strong constitutive expression of HSP26. Furthermore, upstream sequences from the HSP26 gene repressed the constitutive expression of a heterologous heat shock gene. We propose that basal repression and heat-induced depression of transcription play major roles in regulating the expression of HSP26. None of the recombinant constructs that we analyzed separated cis-regulatory sequences responsible for heat shock regulation from those responsible for developmental regulation of HSP26. Depression of HSP26 transcription may be the general mechanism of HSP26 induction in yeast cells. This regulatory scheme is very different from that described for the regulation of most other heat shock genes.
Mol Cell Biol 1990 Dec
PMID:Transcriptional derepression of the Saccharomyces cerevisiae HSP26 gene during heat shock. 212 93

The structure, genomic organization, and temporal pattern of activation of a gene encoding a pathogenesis-related protein (PR1) in potato (Solanum tuberosum) have been analyzed. The gene is rapidly activated in leaves from the potato cultivar Datura, containing the resistance gene R1, in both compatible and incompatible interactions with appropriate races of the late-blight fungus Phytophthora infestans. Activation is also observed in leaves treated with fungal elicitor. The gene occurs in multiple, very similar copies and encodes a polypeptide (Mr = 25,054; pI = 5.5) that is classified as a PR protein by several criteria. Small fragments with great sequence similarity to portions of the two exons were found closely linked to the expressed gene, which altogether represents a simple case of genome organization in potato. The coding sequence of the prp1 gene and the deduced amino acid sequence are strikingly similar to the corresponding sequences of a 26-kDa heat shock protein from soybean.
Mol Plant Microbe Interact
PMID:Structural analysis and activation by fungal infection of a gene encoding a pathogenesis-related protein in potato. 213 26

The 70-kilodalton heat shock protein (hsp70) family members appear to be essential components in a number cellular protein-protein interactions. We report here on the characterization of a new functional region in hsp70, a calmodulin-binding site. We have identified a 21-amino-acid sequence within the hsp70 protein that contains a calmodulin-binding domain. The peptide formed a potential amphipathic alpha helix and bound calmodulin with high affinity. Comparison of amino acid homology of this calmodulin-binding sequence with analogous hsp70 sequences from other species showed a high degree of conservation.
Mol Cell Biol 1990 Mar
PMID:Members of the 70-kilodalton heat shock protein family contain a highly conserved calmodulin-binding domain. 215 82

A DNA-activated protein kinase (DNA-PK) was purified from nuclei of HeLa cells. Activity was associated with a single high-molecular-mass (approximately-300,000 Da) polypeptide when analyzed by gel filtration, denaturing polyacrylamide gel electrophoresis, and Western immunoblotting using a monoclonal antibody that also inhibits enzyme activity. Nuclear localization was indicated by subcellular fractionation and confirmed by immunofluorescence on whole cells. Double-stranded DNA stimulated phosphorylation of the 300-kDa polypeptide in purified preparations as well as phosphorylation of the exogenous substrates alpha-casein, simian virus 40 large T antigen, and the human heat shock protein hsp90. Autophosphorylation led to inactivation of the enzyme. The phosphorylation of casein was stimulated over 30-fold by DNA and was specific for serine and threonine residues. Bovine serum albumin and histone H1 were poor substrates for DNA-PK, and no phosphorylation of immunoglobulin G or histones other than H1 was observed. Supercoiled or heat-denatured DNA and synthetic double-stranded RNA or RNA-DNA copolymers did not stimulate casein phosphorylation by DNA-PK. Interaction of the enzyme with DNA in the absence of exogenous substrates was demonstrated by thermal inactivation and gel mobility shifts. These characteristics identify DNA-PK as distinct from other protein kinases described in the literature and suggest that activation by DNA is an important feature of the enzyme's in vivo function.
Mol Cell Biol 1990 Dec
PMID:A DNA-activated protein kinase from HeLa cell nuclei. 224 66

Steroid hormones, regulators of cell differentiation and proliferation, are believed to play a role in carcinogenesis. Glucocorticoid hormones in particular modulate the expression of a number of proteins implicated in this process. We have investigated the effect of dexamethasone on two cell lines derived from a colon carcinoma, which differ by their tumorigenicity. Dexamethasone was found to inhibit growth of both the progressive (PROb) and the regressive clone (REGb). Upon hormonal treatment, glucocorticoid hormones induced fibronectin secretion by the two clones, whereas PROb cells were found to secrete an additional Mr approximately 43,000 protein. The cellular effect of glucocorticoid hormones being mediated through a specific soluble receptor, we have characterized this protein. The progressive cells (PROb) contained more specific glucocorticoid-binding sites (approximately 170,000 sites per cell) than the regressive ones (REGb cells; approximately 100,000 sites per cell). In both clones, the receptor was associated with the Mr approximately 90,000 heat shock protein to yield large complexes (Stokes radius Rs approximately 7.5 nm), which were dissociated to the same extent upon heat- and salt-treatment. The steroid- and DNA-binding unit of the receptor, characterized under denaturing conditions using an anti-receptor monoclonal antibody was found to be more degraded in the progressive cell line.
J Steroid Biochem Mol Biol 1990 Oct
PMID:Glucocorticoid effects and receptors in two rat colon carcinoma cell lines differing by their tumorigenicity. 226 53

Double labelling and Western blot techniques were used to demonstrate phosphorylation of estradiol receptor. Cells in monolayer culture were incubated with [32P]orthophosphate for 18 h followed by covalent whole cell labelling of the estradiol receptor with tritiated tamoxifen aziridine [( 3H]TA). Labelled receptor was precipitated with the monoclonal antibodies H222 or JS 34/32, coupled to protein A-Sepharose, and purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), or transferred to nitrocellulose paper. Receptor protein was detected on the Western blot with the monoclonal antibody H222 and rabbit anti-rat peroxidase conjugate. Phosphorylated receptor was visualized by autoradiography. Tritium and 32P activities were monitored in the gels. Two phosphorylated forms of the receptor (molecular weights 67 and 50 kDa) have been detected in MCF-7 cells. Estradiol treatment of the cells was found to increase phosphorylation of the receptor. In estradiol-treated cells both phosphorylated receptor forms were present mainly in the nuclear extract. Both forms bound [3H]TA as evidence by SDS-PAGE. [3H]TA binding was abolished by excess non-radioactive estradiol. In addition two phosphorylated proteins of approximately 120 and 90 kDa were regularly coprecipitated with receptor in cytosol. These proteins did not bind [3H]TA. The 90 kDa phosphorylated protein was identified as a heat shock protein (hsp-90).
Mol Cell Endocrinol 1990 Nov 12
PMID:Phosphorylation of the estradiol receptor in MCF-7 human breast cancer cells in culture. 228 77


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