Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
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Microscopic screening of a collection of cold-sensitive mutants of Saccharomyces cerevisiae led to the identification of a new gene, CDC55, which appears to be involved in the morphogenetic events of the cell cycle. CDC55 maps between CDC43 and CHC1 on the left arm of chromosome VII. At restrictive temperature, the original cdc55 mutant produces abnormally elongated buds and displays a delay or partial block of septation and/or cell separation. A cdc55 deletion mutant displays a cold-sensitive phenotype like that of the original isolate. Sequencing of CDC55 revealed that it encodes a protein of about 60 kDa, as confirmed by Western immunoblots using Cdc55p-specific antibodies. This protein has greater than 50% sequence identity to the B subunits of rabbit skeletal muscle type 2A protein phosphatase; the latter sequences were obtained by analysis of peptides derived from the purified protein, a polymerase chain reaction product, and cDNA clones. An extragenic suppressor of the cdc55 mutation lies in BEM2, a gene previously identified on the basis of an apparent role in bud emergence.
Mol Cell Biol 1991 Nov
PMID:CDC55, a Saccharomyces cerevisiae gene involved in cellular morphogenesis: identification, characterization, and homology to the B subunit of mammalian type 2A protein phosphatase. 165 38

Cryoimmunoglobulins are associated with numerous clinical problems ranging from collagen vascular disorders (rheumatoid arthritis and systemic lupus erythematosus) to infectious processes including HIV infection. The precise role of cryoglobulins in the pathophysiology of these disorders remains unresolved. Although cold insolubility may account for some of the observed processes, it cannot explain the entire array of findings in cryoglobulinemia. An alternative hypothesis suggests that the subtle differences responsible for cold precipitation of these proteins renders them intrinsically more sticky, resulting in deposition of cryoimmunoglobulins on vascular surfaces. We have explored this hypothesis by characterizing the binding of monoclonal cold soluble and cryoimmunoglobulins to silica beads as a model biological surface. It is found that monoclonal, type I, IgM and IgG cryoglobulins have only a slight tendency to bind to a greater extent to this surface than cold soluble immunoglobulins. Physical studies utilizing front surface fluorescence measurements and differential scanning calorimetry show surface interaction leads to partial thermal destabilization of the proteins. To a limited extent, this destabilization is more pronounced with the cryoglobulins compared to cold-soluble control homologues. Surface bound IgM cryoimmunoglobulin was also found to fix complement less efficiently than their cold soluble surface bound counterparts. These studies do not strongly support the hypothesis that pathological mechanisms of cryoimmunoglobulins primarily involve abnormal surface interactions, although surface effects could play a limited role in some situations.
Mol Immunol 1991 Sep
PMID:The interaction of cryoimmunoglobulins with a model surface. 165 45

Endothelin-1 (ET-1) is a potent, vasoconstrictive peptide isolated from culture media of vascular endothelial cells. The binding of ET-1 to membrane preparations from rat and bovine lung was studied using radioiodinated ET-1 (125I-ET-1). With both membrane preparations, 125I-ET-1 showed saturable binding to a single class of high affinity sites. Scatchard analysis of the binding data gave dissociation constants (Kd) for ET-1 of 0.22 nM and 0.15 nM, and receptor densities (Bmax) of 6.1 pmol/mg and 2.7 pmol/mg for rat and bovine lung membranes, respectively. Photo-reactive radioiodinated ET-1, N epsilon 9-azidobenzoyl-125I-ET-1, was synthesized and purified as a mono-reactive affinity labeling reagent. This reagent was used for affinity labeling of ET-1 receptor in bovine and rat lung membranes. Photoaffinity labeling followed by sodium dodecyl sulfate gel electrophoresis and autoradiography gave a radiolabeled protein band with an apparent Mr of 34,000 in both membrane preparations. The labeling of this protein band was inhibited by cold ET-1 in a concentration-dependent manner. Labeling was not abolished by unrelated peptides such as angiotensin II and [Arg8]-vasopressin, or by structurally related bee venom apamin. These results indicate that the ET-1 receptor or its ligand binding subunit consists of a 34,000 Da polypeptide.
Mol Cell Endocrinol 1991 Aug
PMID:Affinity labeling of endothelin receptors in bovine and rat lung membranes by N epsilon 9-azidobenzoyl-125I-endothelin-1. 165 62

Since the discovery of a specific membrane binding site for sex steroid binding protein (SBP) in human decidual endometrium and in hyperplastic prostate numerous speculations have been raised on the existence of an additional non-receptor-mediated system for steroid hormone action. In the present work SBP cell membrane binding was investigated in human estrogen target tissues other than those previously studied either in the absence of steroids or in the presence of varying amounts (10(-10)-10(-6) M) of estradiol, testosterone and dihydrotestosterone, respectively. Plasma membranes obtained by differential centrifugation from homogenized samples of pre-menopausal endometrium, endometrium adenocarcinoma, normal liver and post-menopausal breast showed a specific binding of highly purified [125I]SBP: a major displacement of labeled SBP was elicited by radioinert SBP, while no significant displacement occurred when other human plasma proteins were used as cold competitors (molar excess ranging 500-10,000-fold). A specific, time-dependent binding of [125I]SBP was also observed in MCF-7 and in Hep-G2 cell lines. The different patterns of specific binding, observed in membranes from different tissues when SBP was liganded with different sex steroid molecules, leads us to consider the tissue individuality of the receptor as a further entity in the membrane recognition system for SBP.
J Steroid Biochem Mol Biol 1991
PMID:Sex steroid binding protein (SBP) receptors in estrogen sensitive tissues. 165 93

To identify and characterize endothelial cell surface components that bind plasminogen, we used ligand-blotting to study binding of plasminogen to sodium dodecyl sulphate solubilized extracts of human umbilical vein endothelial cells. It was observed that glu-plasminogen bound predominantly to a 45 kDa endothelial cell polypeptide. The interaction of labelled glu-plasminogen with this polypeptide was reversible and specific as the binding could be inhibited by both excess cold lysine and unlabelled glu-plasminogen but not by unrelated proteins. Binding of glu-plasminogen to cell extracts prepared from endothelial cells that had been pretreated with proteinase K was significantly reduced indicating that the 45 kDa polypeptide is a cell-surface protein. The cell-surface localization of the 45 kDa polypeptide was also indicated by the positive interaction of glu-plasminogen with membrane fractions of endothelial cells. Lys-plasminogen also interacted with the 45 kDa polypeptide in a specific manner and reversibility experiments indicated that lys-plasminogen could also displace the bound glu-plasminogen. Since binding of plasminogen to the 45 kDa endothelial cell surface polypeptide was very similar to plasminogen binding to intact endothelial cells, we propose that the 45 kDa protein represents one of the major receptors for plasminogen on human endothelial cells.
Mol Cell Biochem 1991 Dec 11
PMID:Identification of an endothelial cell surface protein that binds plasminogen. 166 40

During cardiac surgery, the heart is infused with cold crystalloid cardioplegic solutions such as St. Thomas' Hospital (StT) solution, which contains high concentrations of K+ and Mg2+. The high K+ and Mg2+ block impulse conduction and inhibit Ca2+ influx, thereby arresting the heart and reducing cardiac oxygen consumption. Nevertheless, myocardial edema and post-operative abnormalities have been noted after cardioplegia and attributed to ischemia and reflow or to hypothermia. We found, however, that cold StT (9 degrees C) was hypotonic and induced cell swelling in the absence of ischemic injury. Cell swelling in cold StT was not due to hypothermia alone, but rather was caused by KCl influx and was prevented by partially replacing Cl- with an impermeant anion. After exposure to cold StT, cells transiently shrank to less than control volume on rewarming in physiological saline (Tyrode's solution, 37 degrees C). The transient shrinkage was blocked by ouabain suggesting that Na+ loading of depolarized hypothermic cells and Na(+)-K+ pump activation on rewarming were responsible. Hypothermic ventricular cells seem to follow Donnan equilibrium, and the product of [K+] x [Cl-] in cardioplegic solutions affects cell volume in the absence of ischemic injury.
J Mol Cell Cardiol 1991 Nov
PMID:Prevention of myocardial intracellular edema induced by St. Thomas' Hospital cardioplegic solution. 166 12

For the electron microscopic identification of asialo GM1-positive cells, fresh-frozen sections fixed with cold acetone and PLP-fixed vibratome sections of adult rat livers were prepared immunocytochemically using the avidin-biotin-peroxidase complex method. Asialo GM1-positive cells were located mainly in the sinusoids, and rarely in Glisson's sheath and portal veins. In the sinusoids, most pit cells, showing the ultrastructural characteristics of large granular lymphocytes (LGL), were positive for asialo GM1 but a few pit cells were asialo GM1-negative. There were several, morphological differences between asialo GM1-positive and -negative pit cells. The asialo GM1-negative pit cells were smaller and had less-developed cell organelles and fewer dense granules, suggesting a more immature stage of development. Almost all the monocytes, segmented neutrophils and eosinophils, and small or large lymphocytes in the sinusoids also showed positive reaction for asialo GM1. In Glisson's sheath, in addition to pit cells and lymphocytes, mast cells were also positive for asialo GM1. In contrast, fixed cells such as liver parenchymal cells, endothelial cells, Kupffer cells and Ito cells within the liver lobules, as well as biliary epithelial cells, smooth muscle cells, fibroblasts, endothelial cells and pericytes in Glisson's sheath were all negative for asialo GM1. Thus, cell surface asialo GM1 expression is not specific for pit cells (LGL) in the rat liver.
Virchows Arch B Cell Pathol Incl Mol Pathol 1991
PMID:Immunoelectron microscopic identification of asialo GM1-positive cells in adult rat liver. 168 55

The presence of mutations in the majority of the genes of cold-adapted strains A/Leningrad/134/17/57 (H2N2), A/Leningrad/134/47/57 (H2N2) and A/PR/8/59/1 (H1N1) of influenza A virus has been demonstrated by the RNA-RNA hybridization with the subsequent electrophoresis of double-stranded RNA in 7.5% polyacrylamide gel. The strains were cultivated 17, 47 and 59 passages in the chicken embryos at 25 degrees C. In the genomes of variants passaged in chicken embryos at optimal temperature of incubation 36 degrees C (hr-variants) the used technique permits identification of a single mutant gene. The obtained data suppose the attenuation of cold-adapted vaccine strains of influenza A virus and their high genetic stability to be a result of selection of the variants obtaining multiple mutations in the genome during passaging of the virions at cold temperature. The attenuation of hr-variants is defined by 1-2 mutations (first of all in HA-gene) that makes understandable their inability to serve as donors for recombinant live influenza vaccines construction.
Mol Gen Mikrobiol Virusol 1990 Nov
PMID:[Features of mutated changes of genomic RNA of cold-adapted and hr-variants of influenza group A virus, detected by RNA:RNA hybridization]. 170 66

CTLs (CD8+) are known to recognize exogenous peptide in the context of class I MHC molecules. We observed that an influenza subtype H1 and H2 cross-reactive CTL clone B7, which was stimulated by a fusion protein containing a portion of HA2 subunit of A/PR/8 virus HA, recognized a synthetic peptide (residues 515-526) of the HA2 subunit of A/PR/8 virus strain. This CTL clone also recognized a structurally disparate NS1 peptide 50-68 of the same A/PR/8 virus. We examined the recognition of the NS1 peptide 50-68 and the HA peptide 515-526 by the subcloned CTL clone, B7-B7. Cold target inhibition experiments showed that the recognition of the HA peptide by the CTL clone B7-B7 could be competed by NS1 peptide-treated target cells and vice versa. The recognition of both NS1 peptide and HA peptide by the CTL clone B7-B7 was restricted by the same allele, H2Kd. In addition, this NS1 peptide requires approximately a 600-fold higher concn for optimal CTL recognition than did the HA peptide. We conclude that the TCR on clone B7-B7 recognizes the HA peptide or the NS1 peptide as comparable complexes with the same class I MHC molecules, although there is no obvious homology in the primary sequences of HA 515-526 and NS1 50-68 peptides. CTLs elicited with certain antigens appear to recognize distinctively different antigens complexed to the same presenting MHC molecule.
Mol Immunol
PMID:Recognition of disparate HA and NS1 peptides by an H-2Kd-restricted, influenza specific CTL clone. 170 32

Viral transformation and DNA-transfection assays were employed to investigate the differential toxic effect of caffeic acid phenethyl ester (CAPE), an extract of the honeybee hive product propolis, on adenovirus type 5 (Ad5)-transformed cloned rat embryo fibroblast (CREF) cells. CAPE inhibited, in a dose-dependent manner, both de novo and carcinogen-enhanced transformation of CREF cells by H5hr1, the cold-sensitive (cs) host-range mutant of Ad5. CAPE had a selective inhibitory effect on Ad5-induced transformation when a wild-type (wt) Ad5 E1A gene or a cs Ad5 E1A gene (at 37 degrees C, but not at 32 degrees C) was cotransfected into CREF cells with a dominant-acting bacterial hygromycin-resistance gene. A requirement for the expression of Ad5 E1A-encoded mRNAs and transforming proteins and sensitivity to CAPE was demonstrated using CREF cells stably transformed by a cs Ad5 E1A gene and an Ad5 E1A gene under the transcriptional control of a mouse mammary tumor virus promoter. To distinguish between the effects of the two Ad5 E1A-encoded proteins of 289 amino acids (aa) and 243 aa, CREF cells were stably transformed with cDNAs encoding either the 13S or the 12S E1A mRNA. CREF cells expressing the 13S E1A-encoded 289-aa protein were more sensitive to the growth-suppressing effect of CAPE than cells producing only the 12S E1A-encoded 243-aa protein. However, the growth-suppressing and toxic effects of CAPE were greatest in cells expressing both E1A-encoded transforming proteins. Analysis of the effect of CAPE on E1A and beta-actin gene expression in wt and cs E1A and H5hr1-transformed CREF cells indicated that low levels of CAPE, which were growth suppressive, did not selectively suppress E1A expression. These results demonstrated that cellular changes induced in CREF cells by the 13S E1A-encoded 289-aa protein of Ad5, when expressed alone or in combination with the 12S E1A-encoded 243-aa protein, rendered transformed cells sensitive to the growth-suppressing and toxic effects of CAPE.
Mol Carcinog 1991
PMID:Suppression of adenovirus type 5 E1A-mediated transformation and expression of the transformed phenotype by caffeic acid phenethyl ester (CAPE). 171 5


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