Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In electron microscopic observations on the villous cytotrophoblast in pathologic human placentas we find, besides a general increase of the amount of Langhans cells, significant ultrastructural differences according to the different diseases in pregnancy. Diabetes mellitus: the most striking observations are small, extremely electron dense mitochondria and a lot of intracellular filaments in a hydropic cytoplasm. Rh-incompatibility: according to the stage of placental damage the Langhans cells show a different structure. In light cases we find hydrolic cells with normal mitochondria as well as swollen ones. The plasmalemm shows a lot of foldings and dentations with the syncytium. In serious cases of rh-incompatibility the Langhans cells cover the trophoblastic basal membrane completely. Their electron density is even higher than that of the syncytium. Characteristic lysosomes appear. In the most serious cases the syncytium is completely destroyed and maximal hydropic Langhans cells cover the villi. EPH-gestosis: the Langhans cells show different phases of differentiation, but no other characteristic criteria. The importance of the Langhans cells for the regeneration of the syncytotrophoblast is discussed. Mitochondria and rough endoplasmic reticulum are obviously not formed in the syncytium but they must be regenerated by taking up Langhans cells by syncytial fusion.
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PMID:[The ultrastructure of Langhans cells in pathologic human placentas (author's transl)]. 40 85

The ultrastructure of normal full-term placentae and of placentae of patients with EPH-gestosis was studied. To minimalize artificial changes puncture biopsies during cesarian section were performed. The main ultrastructural alterations in cases of EPH-gestosis can be summarized as follows: loss of the characteristic three-zonal pattern, increased deposits of fibrinoid, rarefication of microvilli, dilatation of the endoplasmic reticulum and of the Golgi apparatus.
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PMID:Ultrastructure of the syncytiotrophoblast of the human term placenta in EPH-gestosis. 52 88

The lipid composition of highly purified Flury strain of rabies virus (HEP) propagated in BHK-21 cells in a chemically defined medium was observed to be 6.7% neutral lipids, 15.8% phospholipids, and 1.5% glycolipids. In the virion, phosphatidylethanolamine, phosphatidylcholine, and sphingomyelin were the most abundant phospholipids, accounting for 90% of the total, and the molar ratio of cholesterol to phospholipid was 0.48. Uninfected BHK-21 cell membranes were obtained by nitrogen cavitation techniques and separated by density gradient centrifugation, and the membranes were assayed for purity using 5'-nucleotidase, cytochrome oxidase, and reduced nicotinamide adenine dinucleotide phosphate diaphorase activities. Lipids of the plasma membrane were enriched in cholesterol, phosphatidylcholine, and phosphatidylethanolamine. In contrast, membranes of the endoplasmic reticulum were enriched in phosphatidylcholine, but contained smaller amounts of phosphatidylethanolamine and sphingomyelin. Comparison of the fatty acyl chains of virus and membranes from uninfected cells revealed the virion to have the lowest ratio of C18:1 to C18:0 (1.771), compared with values of about 3.0 for the plasma membrane and endoplasmic reticulum. Total polyenoic fatty acids were enriched in the plasma membrane, whereas the virus contained higher amounts of total saturates than either of the two membrane preparations. Analysis of the polar and neutral lipid fractions as well as the acyl chain analysis suggests the virion has a lipid composition that is intermiediate to that of the plasma membrane and endoplasmic reticulum and is consistent with the view that numerous viral particles are synthesized de novo by not utilizing a preexisting membrane template. From the ratio of cholesterol to phospholipid of 0.48, we calculated that 1.92 X 10(5) molecules of lipid would cover 4.14 X 10(4) nm2 in the form of a bilayer. Considerations of the molecular dimensions of the rabies envelope (total surface area, 5 X 10(4) nm2) as a bilayer suggest that some penetration of lipids by envelope proteins (M and G) is necessary.
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PMID:Lipids of rabies virus and BHK-21 cell membranes. 55 73

The HER2 (c-erbB-2) gene encodes a protein, p185HER2, which possesses all of the structural characteristics and functional properties of a growth factor receptor, although its ligand has not yet been well characterized. HER2 is the human homolog of the rat proto-oncogene neu and is closely related to the gene encoding the epidermal growth factor receptor. Amplification of this gene and overexpression have been found to be a prognostic criterion for a 30% subpopulation of human breast cancer patients. In this study, we investigated the role of the transmembrane-spanning sequence in the biosynthesis and localization of p185HER2. A truncation mutant lacking the cytoplasmic and transmembrane domains was glycosylated and efficiently secreted. However, a mutant lacking only the transmembrane-spanning sequence was incompletely glycosylated and failed to reach the cell surface. Unexpectedly, although this deletion mutant was retained in the endoplasmic reticulum membrane, it was still able to transform NIH 3T3 cells when expressed at high levels.
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PMID:Cell transformation potential of a HER2 transmembrane domain deletion mutant retained in the endoplasmic reticulum. 168 81

Interaction of epidermal growth factor (EGF) with its specific receptor (EGFR) was explored in the intact rat small intestine and in highly purified isolated enterocyte membrane preparations. Despite the fact that the EGF ligand is known to be present at physiological concentrations within the intestinal cavity, no significant binding of the ligand to the brush border surface was observed. Instead, binding of EGF to the EGFR was confined to other membrane populations, and correlation of ligand interaction with the laterobasal membranes (LBM) was nearly perfect (p less than 0.001) across a special equilibrium gradient enriched in brush border and LBM but devoid of intracellular membranes. Specific binding to another minor population of intracellular membranes that migrated to a position less dense than typical endoplasmic reticulum-Golgi vesicles on equilibrium gradients was also observed. Immunocytochemical exposure of intestine to EGFR antibody confirmed the localization of the EGFR to LBM and intracellular membranes. As estimated from the intensity of the staining, there may be immunologically active but nonbinding receptor species in the intracellular membrane compartment. Thus, despite the secretion of EGF into the intestinal lumen, the growth and maturational effects of EGF probably result from a specific interaction between EGF and EGFR solely at the laterobasal surface of the enterocyte. The functional role of the intracellular membrane species of EGFR, which remains to be established, may involve a source of inactive receptor that can be rapidly recruited and transferred to the LBM surface under changing environmental conditions.
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PMID:Epidermal growth factor receptor of the intestinal enterocyte. Localization to laterobasal but not brush border membrane. 291 82

We investigated the biosynthesis of the human insulin receptor in IM-9 lymphocytes and HEP-G2 hepatoma cells. Cells were first pulse labeled for 15 min with [35S]methionine and then chased for up to 4 h. At each time, the cells were solubilized in 1% Triton X-100; the insulin receptor was immunoprecipitated and then analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (6%) and fluorography. At 15 min, a major precursor protein of 190,000 Mr was precipitated. During the chase period, two smaller proteins became apparent, which evolved into two major species of 130,000 and 95,000 Mr, the mature alpha- and beta-subunits, respectively. When IM-9 cells were trypsinized after pulse chase, the alpha- and beta-subunits were completely digested, whereas the 190,000-Mr precursor was unaffected. 125I-surface labeling of cells, followed by immunoprecipitation, revealed the presence of only the alpha- and beta-subunits, indicating that only these two species were on the cell surface. To study this biosynthetic pathway, several inhibitors were used (tunicamycin, monensin, and swainsonine). These inhibitors revealed the following. The receptor is first synthesized as a 170,000-Mr protein that is cotranslationally N-glycosylated to yield a high-mannose 190,000-Mr precursor. This precursor is rapidly transported from the endoplasmic reticulum to the Golgi apparatus where it is cleaved into two subunits of 120,000 Mr (alpha) and 90,000 Mr (beta). These subunits then increase in molecular weight by processing of the high-mannose oligosaccharides to the low-mannose complex type. The two subunits then migrate to the cell surface where they function to transmit the insulin signal.
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PMID:Biosynthesis and processing of the human insulin receptor. 372 Oct 67

This report presents the ultrastructural features of a congenital epulis. The granular cells of the epulis were packed with numerous membrane bound cytoplasmic granules containing particles, small vesicles, and electron-dense materials. These granules were negative in immunohistochemical reaction for CEA (DAKO PAP KIT). Cytoplasmic organelles such as mitochondria, rough surfaced endoplasmic reticulum, and Golgi apparatus, were absent. Nuclei were markedly indented. Occasionally, banded intracellular collagen fibrils were observed within the cytoplasm. Some of these fibrils were surrounded by a limiting membrane, whereas others appeared to lie free in the cytoplasm. The collagen fibrils were also seen within a deep invagination of the cell surface. There was no basal lamina around the granular cells. Sporadically, mast cells with many granules containing lamellar formations were found between the granular cells. These observations support the idea that granular cells of the congenital epulis are derived from mesenchymal cells, probably fibroblasts.
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PMID:Ultrastructure of the congenital epulis. 641 6

Type II integral membrane proteins are anchored by a signal-peptide/membrane-anchor domain (SA domain) located near their N-terminus, whereas type I membrane proteins are anchored by stop-transfer sequences usually located near the C-terminus. In this study we have attempted to transform neutral endopeptidase-24.11 (EC 3.4.24.11; NEP), a type II membrane protein, into a type I membrane protein. Three type I mutant proteins were constructed by fusion of topogenic sequences to the C-terminus of SecNEP, a soluble form of NEP. The first two type I mutants, SecNEP-TMC and SecNEP-TMIC, were constructed by fusing in frame the cytosolic and SA domains of NEP to the C-terminus of SecNEP. These two fusion proteins differ only in the orientation of the cytosolic tail. The third type I mutant, SecNEP-ACE, was constructed by fusing in frame the stop-transfer and cytosolic domains of angiotensin I-converting enzyme (EC 3.4.15.1; ACE) to the C-terminus of SecNEP. Our results suggest that: (1) the NEP ectodomain can be anchored with a type I topology in the endoplasmic reticulum (ER) membrane by both NEP and ACE topogenic sequences; (2) SecNEP-TMC and SecNEP-TMIC were transport-incompetent and needed proteolytic cleavage in the C-terminal region to leave the ER, whereas SecNEP-ACE was transported out of the ER as a type I membrane protein. Therefore we concluded that the nature of topogenic sequences determines the transport-competence of topological mutants of neutral endopeptidase-24.11.
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PMID:The nature of topogenic sequences determines the transport competence of topological mutants of neutral endopeptidase-24.11. 749 41

Two anti-nerve growth factor receptor (LNGFR or p75NGFR) antibodies, Me20.4 and Me8211, label stromal cells with dendritic features in fresh smears and in formalin-fixed, paraffin-embedded human bone marrow (BM). The LNGFR+ cells have an oval nucleus, a scanty cytoplasm with long dendrites that intermingle with the hematopoietic cells, line the abluminal side of sinus endothelial cells, and provide the scaffold for the hematopoietic marrow. At the electron microscopy level, the immunogold tag labels the body and the long branching dendrites of fibroblast-like cells with scanty cytoplasm containing mitochondria, endoplasmic reticulum, and dense bodies. The LNGFR+ cells are positive for alkaline phosphatase, reticulin, collagen III, vimentin, TE-7, and CD13 but negative for endothelial (vWF, CD34, Pal-E), neural (CD56, neurofilament) and leukocyte markers (CD45, CD68). The LNGFR+ stromal cells appear in the fetal BM before the hematopoietic activity begins, originate from the vessel adventitia, and radiate in the Bm cavity. Long-term BM culture (LTBMC) in vitro contain LNGFR+ stromal cells. We document the presence of RNA message for the low- (LNGFR) and the high-affinity NGF receptor (NTRK1) by using RT-PCR on fresh BM aspirate and on LTBMC. BM biopsies from patients with hematologic fibrogenic diseases and in cytokine-treated cancer patients are evaluated for LNGFR+ cells: the amount of stained cells is correlated with the traditional reticulin stain in cases of myelofibrosis, therapy-related myelodysplasia, leukemia, and detected an increase of stromal cells in cytokine-treated patients. The anti-LNGFR antibodies represent a specific membrane marker for the adventitial reticular cells (ARC) of the human marrow and allow precise evaluation and quantitation of this important BM microenvironment component in vivo and in vitro.
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PMID:Bone marrow stroma in humans: anti-nerve growth factor receptor antibodies selectively stain reticular cells in vivo and in vitro. 768 1

We have studied the role of intracellular calcium sequestration on human immunodeficiency virus (HIV) production by latently infected T-lymphocytic cells. Inhibition of the sarco-endoplasmic reticulum-type calcium transport ATPases by thapsigargin or cyclopiazonic acid induced activation of HIV production in the CEM-derived ACH-2 cells. An approximately 50% depletion of the thapsigargin-sensitive calcium pools as measured fluorimetrically of Indo-loaded cells fully activated virus production. Viral activation was manifest by increases in soluble viral core p24 production, increases in cellular immunofluorescent staining for viral antigens, and increased viral transcription as measured by HIV long terminal repeat-directed expression of the chloramphenicol acetyltransferase reporter gene. Virus induction could be blocked in a dose-dependent manner by the calcium channel blocker econazole. Virus production by the Jurkat-derived HIV-1-inducible J1.1 cells was not significantly stimulated by thapsigargin. These data indicate that intracellular calcium pool function is involved in the control of the transcription of proviral HIV in a cell type-specific manner within the T-lymphoid lineage and that ACH-2 cells represent a useful model for the study of calcium dependent activation of the transcription of proviral HIV.
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PMID:Stimulation of HIV expression by intracellular calcium pump inhibition. 773 Mar 32


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