Endoplasmic reticulum

Chapter 3 (part c) provides knowledge of the cytoplasm. This chapter describe the composition of the cytosol; discuss the structure and function of mitochondria; discuss the structure and function of ribosomes, the endoplasmic reticulum, and the Golgi apparatus, including functional interrelationships among these organelles; compare the functions of lysosomes and peroxisomes.

30p tangtuy07 02-04-2016 48 2   Download

LƯỚI NỘI BÀO KHÔNG HẠT: SMOOTH ENDOPLASMIC RETICULUM - SER + CÓ Ở NHIỀU LOẠI TB: TẠO HẠT CHUYÊN BIỆT, LƯỚI NỘI BÀO CƠ … + DẠNG ỐNG, NỐI VỚI NHAU VÀ VỚI MÀNG BÀO TƯƠNG + KHÔNG CÓ POLYRIBOSOM (hạt)

19p lumia_12 19-07-2013 100 5   Download

2-Aminoethoxydiphenyl Borate (2-APB) has been extensively used recently as a membrane permeable modulator of inositol-1,4,5-trisphosphate-sensitive Ca2+ channels and store-operated Ca2+ entry. Here, we report that 2-APB is also an inhibitor of sarco/endoplasmic reticulum Ca2+ATPase (SERCA) Ca2+ pumps, and additionally increases ion leakage across the phospholipid bilayer. Therefore, we advise caution in the interpretation of results when used in Ca2+ signalling experiments.

10p system191 01-06-2013 40 4   Download

This review provides a comparative overview of recent developments in the modelling of cellular calcium oscilla-tions. A large variety of mathematical models have been developed for this wide-spread phenomenon in intra- and intercellular signalling. From these, a general model is extracted that involves six types of concentration variables: inositol 1,4,5-trisphosphate (IP3), cytoplasmic, endoplasmic reticulum and mitochondrial calcium, the occupied binding sites of calcium buffers, and the fraction of active IP3 receptor calciumrelease channels....

23p research12 29-04-2013 27 3   Download

In this study, we demonstrate that the folding and assembly of IgG in transgenic tobacco plants is orchestrated by BiP (binding protein), an endoplasmic reticulum resident chap-erone. Expression of BiP and calreticulin was examined in transgenic tobacco plants that express immunoglobulin chains, either singly or in combination to form IgG anti-body. BiP mRNA expression was lowest in wild-type nontransformed plants and those that expressed immuno-globulin light chain alone.

10p tumor12 22-04-2013 35 3   Download

The present study was conducted on human Jurkat T-cell lines in order to elucidate the role of phospholipase A2in capacitative calcium entry. We have employed thapsigar-gin (TG)that induces increases in [Ca 2+ ] i by emptying the calcium pool of endoplasmic reticulum, followed by capacitative calcium entry. We designed a Ca 2+ free/Ca 2+ reintroduction (CFCR)protocol for the experiments, conducted in Ca 2+ -free medium.

7p tumor12 22-04-2013 30 2   Download

The thyrotropin receptor (TSHR) is a member of the G protein-coupled receptor superfamily. It has by now been clearly established that the maturation of the glycopro-teins synthesized in the endoplasmic reticulum involves interactions with molecular chaperones, which promote the folding and assembly of the glycoproteins. In this study, we investigated whether calnexin (CNX), calreti-culin (CRT) and BiP, three of the main molecular chap-erones present in the endoplasmic reticulum, interact with the TSHR and what effects these interactions might have on the folding of the receptor....

8p tumor12 22-04-2013 35 4   Download

The chaperone calreticulin is a highly conserved eukaryotic protein mainly located in the endoplasmic reticulum. It contains a free cysteine SH group but does not form disul-fide-bridged dimers under physiological conditions,indica-ting that the SH group may not be fully accessible in the native protein. Using PAGE,urea gradient gel electro-phoresis,capillary electrophoresis and MS,we show that dimerization through the SH group can be induced by lowering the pH to 5–6,heating,or under conditions that favour partial unfolding such as urea concentrations above 2.

9p tumor12 20-04-2013 39 4   Download

BAP31 is a 28-kDa integral membrane protein of the endoplasmic reticulumwhose cytosolicdomaincontains two caspase recognition sites that are preferentially cleaved by initiator caspases,such as caspase-8. Recently,we reported that the caspase-resistant BAP31 inhibited Fas-mediated apoptotic membrane fragmentation and the release of cytochromec from mitochondria in KB epithelial cells (Nguyen M.,Breckenridge G.,Ducret A &Shore G. (2000) Mol. Cell.Biol.20,6731–6740).

8p tumor12 20-04-2013 34 4   Download

The formation of disulfide bonds in the endoplasmic reti-culum requires protein disulfide isomerase (PDI) and endoplasmic reticulum oxidoreductin 1 (ERO1) that reoxi-dizes PDI. We report here that the expression of the rat, mouse andhumanhomologues ofERO1-Likeproteinabut not of the isoform ERO1-Lbare stimulated by hypoxia in rats vivo and in rat, mouse and human cell cultures.

8p fptmusic 16-04-2013 61 4   Download

Most of the examples of protein translocation across a membrane (such as the import of classical secretory proteins into the endoplasmic reticulum, import of proteins into mitochondria and peroxisomes, as well as protein import into and export from the nucleus), are understood in great detail.

11p fptmusic 16-04-2013 39 4   Download

Several protein toxins, such as the potent plant toxin ricin, enter mamma-lian cells by endocytosis and undergo retrograde transport via the Golgi complex to reach the endoplasmic reticulum (ER). In this compartment the catalytic moieties exploit the ER-associated degradation (ERAD) pathway to reach their cytosolic targets. Bacterial toxins such as cholera toxin or Pseudomonasexotoxin A carry KDEL or KDEL-like C-terminal tetrapep-tides for efficient delivery to the ER.

13p fptmusic 12-04-2013 45 3   Download

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a recently described Ca 2+ mobilizing messenger, and probably the most potent. We briefly review its unique properties as a Ca 2+ mobilizing agent. We present arguments for its action in targeting acidic calcium stores rather than the endoplasmic reticulum. Finally, we discuss possible biosynthetic pathways for NAADP in cells and candidates for its target Ca 2+ release channel, which has eluded identification so far.

9p fptmusic 11-04-2013 43 2   Download

Eukaryotic cells respond to the accumulation of unfolded proteins in the endoplasmic reticulum (ER). In this case, so-called unfolded protein response (UPR) genes are induced. We determined the transcriptional expression ofArabidopsis thaliana UPRgenes by fluid microarray analysis of tunicamycin-treated plantlets. Two hundred and fifteen up-regulated genes and 17 down-regulated ones were identified.

16p fptmusic 11-04-2013 31 1   Download

Hu-K4 is a human protein homologous to the K4L protein of vaccinia virus. Due to the presence of two HKD motifs, Hu-K4 was assigned to the family of Phospholipase D proteins although so far no catalytic activity has been shown. The Hu-K4 mRNA is found in many human organs with highest expression levels in the central nervous system. We extended the ORF of Hu-K4 to the 5¢ direction. As a consequence the protein is 53 amino acids larger than originally predicted, now harbouring a putative transmembrane domain....

0p awards 06-04-2013 39 3   Download

Cytosolic phospholipase A2-a(cPLA2-a) is a calcium-activated enzyme that plays an important role in agonist-induced arachidonic acid release. In endothelial cells, free arachidonic acid can be converted subsequently into prostacyclin, a potent vasodilator and inhibitor of platelet activation, through the action of cyclooxygenase (COX) enzymes. Here we study the relocation of cPLA2 -a in human EA.hy.926 endothelial cells following stimulation with the calcium-mobilizing agonist, A23187.

13p awards 06-04-2013 37 3   Download

Metachromatic leukodystrophy is a lysosomal storage disorder caused by a deficiency of arylsulfatase A (ASA). Biosynthesis studies of ASA with vari-ous structure-sensitive monoclonal antibodies reveal that some epitopes of the enzyme form within the first minutes of biosynthesis whereas other epi-topes form later, between 10 and 25 min. When we investigated 12 various ASAs, with amino acid substitutions according to the missense mutations found in metachromatic leukodystrophy patients, immunoprecipitation with monoclonal antibodies revealed folding deficits in all 12 mutant ASA enzymes....

0p awards 06-04-2013 24 2   Download

Human UDP-glucuronosyltransferase 1A (UGT1A) isoforms are endoplas-mic reticulum (ER)-resident type I membrane proteins responsible for the detoxification of a broad range of toxic phenolic compounds. These pro-teins contain a C-terminal stop transfer sequence with a transmembrane domain (TMD), which anchors the protein into the membrane, followed by a short cytosolic tail (CT).

9p awards 05-04-2013 35 4   Download

The leukocyte-derived arginine aminopeptidase (L-RAP) is the second ami-nopeptidase localized in the endoplasmic reticulum (ER) processing anti-genic peptides presented to major histocompatibility complex (MHC) class I molecules. In this study, the genomic organization of the gene encoding human L-RAP was determined and the regulatory mechanism of its expres-sion was elucidated.

13p awards 05-04-2013 54 5   Download

To better define the mechanism of membrane protein insertion into the membrane of the endoplasmic reticulum, we measured the kinetics of translocation across microsomal membranes of the N-terminal lumenal tail and the lumenal domain following the second transmembrane segment (TM2) in the multispanning mouse protein Cig30. In the wild-type protein, the N-terminal tail translocates across the membrane before the down-stream lumenal domain.

0p awards 05-04-2013 46 2   Download