SEARCH · PubMed Health

Results for “Subcellular localization”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources

PubMed1981

Subcellular Localization of Dhurrin beta-Glucosidase and Hydroxynitrile Lyase in the Mesophyll Cells of Sorghum Leaf Blades.

Studies with purified mesophyll and epidermal protoplasts and bundle sheath strands have shown that the cyanogenic glucoside dhurrin (p-hydroxy-(S)-mandelonitrile-beta-d-glucoside) is localized in the epidermis of sorghum leaves whereas the enzymes involved in its degradation (dhurrin beta-glucosidase and hydroxynitrile lyase) are localized in the mesophyll tissue (Kojima M, JE Poulton, SS Thayer, EE Conn 1979 Plant Physiol 63: 1022-1028). The subcellular localization of these enzymes has now been examined using linear 30 to 55% (w/w) sucrose gradients by fractionation of mesophyll protoplast components. The hydroxynitrile lyase is found in the supernatant fractions suggesting a cytoplasmic (soluble cytoplasm, microsomal or vacuolar location). The dhurrin beta-glucosidase (dhurrinase) is particulate and mostly chloroplast-associated. The dhurrinase activity peak has a shoulder of activity more dense than that of the intact chloroplasts. This shoulder does not coincide with markers of any other cell fraction.In studies of chloroplasts isolated from ruptured mesophyll protoplasts by differential, low-speed centrifugation, the dhurrinase partitions in the same manner as the chloroplast marker triose phosphate dehydrogenase. Chloroplast localization of the beta-glucosidase has also been shown in histochemical studies using 6-bromo-2-naphthyl-beta-d-glucoside substrate coupled with fast Blue B.

Journal Article↗

PubMed2006

The autophagy-related kinase UNC-51 and its binding partner UNC-14 regulate the subcellular localization of the Netrin receptor UNC-5 in Caenorhabditis elegans.

UNC-51 and UNC-14 are required for the axon guidance of many neurons in Caenorhabditis elegans. UNC-51 is a serine/threonine kinase homologous to yeast Atg1, which is required for autophagy. The binding partner of UNC-51, UNC-14, contains a RUN domain that is predicted to play an important role in multiple Ras-like GTPase signaling pathways. How these molecules function in axon guidance is largely unknown. Here we observed that, in unc-51 and unc-14 mutants, UNC-5, the receptor for axon-guidance protein Netrin/UNC-6, abnormally localized in neuronal cell bodies. By contrast, the localization of many other proteins required for axon guidance was undisturbed. Moreover, UNC-5 localization was normal in animals with mutations in the genes for axon guidance proteins, several motor proteins, vesicle components and autophagy-related proteins. We also found that unc-5 and unc-6 interacted genetically with unc-51 and unc-14 to affect axon guidance, and that UNC-5 co-localized with UNC-51 and UNC-14 in neurons. These results suggest that UNC-51 and UNC-14 regulate the subcellular localization of the Netrin receptor UNC-5, and that UNC-5 uses a unique mechanism for its localization; the functionality of UNC-5 is probably regulated by this localization.

Animals↗

PubMed1991

Subcellular localization of blood group A substance produced by pancreatic adenocarcinoma induced in hamsters by N-nitrosobis(2-oxopropyl)amine (BOP) and by its cell line (PC-1).

The subcellular localization and biochemical characteristics of blood group A antigen were studied by immunogold methods and by SDS-PAGE and Western blotting procedures in N-nitrosobis)2-oxopropyl)amine (BOP)-induced pancreatic cancer (PC) in Syrian hamsters, in the pancreatic cancer cell line (PC-1) derived from a primary induced pancreatic cancer, and in intrapancreatic and subcutaneous transplants of PC-1 cells. Normal hamster duodenal epithelial cells expressing A antigen were compared with the normal hamster pancreas (lacking A antigen), human PC tissues from patients with blood group A and human PC cell lines. Blood group A antigen was present on the membrane of hamster duodenal cells, but was absent in the normal pancreatic cells. A antigen was localized mainly on the cell membrane of the hamster cancer cells both in vivo and in vitro. Glycoproteins with blood group A specificity were observed by SDS-PAGE and Western blotting procedures in the membrane fraction of PC-1 cells, with a major component of molecular mass of approximately 120 kd. Similar migration patterns were observed in the primary induced PC and in subcutaneous and intrapancreatic transplants of PC-1 cells. Membrane preparations from cell lines derived from two primary pancreatic cancers from patients of blood group A and from human pancreatic cell lines, CD11 and CD18, showed a major A reactive component with a molecular mass similar to that found in the hamster PC cells. These findings suggest that: (i) both the hamster and human PC cells in vitro produce glycoproteins with blood group A specificity of similar molecular masses; (ii) differences exist in the structure of the glycoprotein immunoreactive with the anti-A antigen between the normal and cancerous cells; and (iii) differences exist in the molecular mass of the anti-A reactive substance between hamsters and human PC cells and between tissues in vivo and in vitro.

ABO Blood-Group System↗

PubMed2004

Subcellular localization of MAK-V/Hunk protein kinase expressed in COS-1 cells.

MAK-V/Hunk is a MARK/Par-1-related protein kinase, whose function is unknown. We studied the subcellular localization of MAK-V/Hunk in COS-1 cells by immunofluorescence. It has a nucleocytoplasmic distribution and is localized to the centrosome, as indicated by co-localization with gamma-tubulin. A putative kinase-deficient mutant, with a mutation in the invariant lysine residue in the catalytic domain, was not targeted to the nucleus or centrosome. These results suggest that the nuclear and centrosomal targeting of MAK-V/Hunk is specific, and is likely to be coupled to its catalytic activity.

Active Transport, Cell Nucleus↗

PubMed2004

Analysis of HIV-1 viral infectivity factor-mediated proteasome-dependent depletion of APOBEC3G: correlating function and subcellular localization.

To study how HIV-1 viral infectivity factor (Vif) mediates proteasome-dependent depletion of host factor APOBEC3G, functional and nonfunctional Vif-APOBEC3G interactions were correlated with subcellular localization. APOBEC3G localized throughout the cytoplasm and co-localized with gamma-tubulin, 20 S proteasome subunit, and ubiquitin at punctate cytoplasmic bodies that can be used to monitor the Vif-APOBEC3G interaction in the cell. Through immunostaining and live imaging, we showed that a substantial fraction of Vif localized to the nucleus, and this localization was impaired by deletion of amino acids 12-23. When co-expressed, Vif exhibited more pronounced localization to the cytoplasm and reduced the total cellular levels of APOBEC3G but rarely co-localized with APOBEC3G at cytoplasmic bodies. On the contrary, Vif(C114S), which is inactive but continues to interact with APOBEC3G, stably associated with APOBEC3G in the cytoplasm, resulting in complete co-localization at cytoplasmic bodies and a dose-dependent exclusion of Vif(C114S) from the nucleus. Following proteasome inhibition, cytoplasmic APOBEC3G levels increased, and both proteins co-accumulated nonspecifically into a vimentin-encaged aggresome. Furthermore in the presence or absence of APOBEC3G, Vif localization was significantly altered by proteasome inhibition, suggesting that aberrant localization may also contribute to the loss of Vif function. Finally mutations at Vif Ile(9) disrupted the ability of Vif or Vif(C114S) to coimmunoprecipitate and to co-localize with APOBEC3G, suggesting that the N terminus of Vif mediates interactions with APOBEC3G. Taken together, these results demonstrate that cytoplasmic Vif-APOBEC3G interactions are required but are not sufficient for Vif to modulate APOBEC3G and can be monitored by co-localization in vivo.

APOBEC-3G Deaminase↗

PubMedDate not supplied

Subcellular localization of the enzymes of the arginine dihydrolase pathway in Trichomonas vaginalis and Tritrichomonas foetus.

The enzymes of the arginine dihydrolase pathway were demonstrated in Tritrichomonas foetus and their subcellular localization determined for both T. foetus and Trichomonas vaginalis. Ornithine carbamyltransferase (anabolic and catabolic activities), ornithine decarboxylase and carbamate kinase activity were localized predominately (56-80%) in the non sedimentable fraction of both species. A large proportion (35-40%) of the arginine deiminase was, however, recovered in the large granular fraction, and this distribution was unchanged by increasing the ionic strength of the buffer. Upon density gradient centrifugation the particles containing arginine deiminase activity had an isopycnic density of 1.09 g/ml in percoll, and separated from hydrogenosomes (1.18 g/ml) and lysosomes (1.12 g/ml). Arginine deiminase was also the only enzyme of the dihydrolase pathway which demonstrated latency upon treatment of the 1.09 g/ml fraction with non-ionic detergents. The results demonstrate the presence of the arginine dihydrolase pathway in T. foetus and indicate that at least a portion of the arginine deiminase in trichomonads is membrane associated.

Animals↗

PubMed1996

Modification of the cytoplasmic domain affects the subcellular localization of Golgi glycosyl-transferases.

Our goal was to engineer a Golgi glycosyltransferase epitope-tagged on its cytoplasmically exposed, short, N-terminal domain that gave normal subcellular localization. Partial replacement of the cytoplasmic tail of human alpha-2,6-sialyltransferase (SialylT) with the negatively charged myc or FLAG epitope resulted in almost complete mislocalization of the chimera expressed in Vero cells. A granular cytoplasmic staining pattern was seen by immunofluorescence. Spacing the negatively charged residues progressively outward from the negative N-terminus resulted in increasingly more normal localization of myc or FLAG-tagged protein to a juxtanuclear Golgi-like distribution. Substitution of a neutrally charged VSV-G sequence for these tags resulted in normal localization of the chimera to the juxtanuclear Golgi region. Insertion of the myc epitope within the N-terminal domain of the short form of bovine beta-1,4-galactosyltransferase (GalT) gave a chimeric protein that mislocalized in BHK cells. No signal was detected with a monoclonal anti-epitope antibody indicating that the myc epitope was masked. Placement of myc or FLAG epitopes at the NH2-terminus of human N-acetylglucosaminyltransferase I (GlcNAc-T) resulted in chimeric proteins that in Vero cells displayed little Golgi localization. We conclude that positioning of negative charge, in particular, close to the membrane, typically produces a failure of type II Golgi glycosyltransferases to exit the ER/CGN, presumably due to quality control mechanisms. These proteins may be successfully epitope-tagged on their N-terminal domain either using a neutral or positively charged sequence or spacing any negatively charged sequence out from the membrane.

Amino Acid Sequence↗

PubMed1993

Subcellular localization of tau mRNA in differentiating neuronal cell culture: implications for neuronal polarity.

A primary neuronal cell culture derived from whole brains of fetal rats was used to analyze the subcellular localization of tau mRNA, employing nonisotopic detection by in situ hybridization. The culture exhibited a developmental differentiation pattern previously described for neuronal cells in vivo; i.e., a transition from immature to mature tau isoforms as well as segregation of tau into the axons. Our results demonstrate that unlike tubulin mRNA, which is confined to cell bodies, or MAP2 mRNA, which extends into dendrites, tau mRNA was observed to enter the proximal portion of the axon. This sorting of tau mRNA might explain how the tau protein could be selectively delivered to the axon and could have important implications for the development of neuronal polarity.

Animals↗

PubMed2007

Molecular determinants of the subcellular localization of the Drosophila Bcl-2 homologues DEBCL and BUFFY.

The Bcl-2-family of proteins localize to intracellular membranes via a C-terminal hydrophobic membrane anchor (MA) domain, to exert their antiapoptotic or proapoptotic functions. In Drosophila, both Bcl-2 family members, DEBCL and BUFFY, contain an MA. In DEBCL the MA is necessary for the localization of protein to mitochondria and for its proapoptotic activity. BUFFY is highly similar to DEBCL but its localization and function are not clearly defined. Here, we report on comparative analysis of BUFFY and DEBCL to decipher the molecular basis for their subcellular localization. We show that these two proteins localize to distinct intracellular membranes, DEBCL predominantly to mitochondria and BUFFY to endoplasmic reticula (ER). Our results suggest that the MA-flanking residues in DEBCL, homologous to Bcl-X(L), are required for the targeting of DEBCL to mitochondria. The C-terminal positively charged residues present in DEBCL are absent in BUFFY, which allows for its localization to ER. The MA in both proteins is required for the correct targeting and proapoptotic activities of these proteins. Interestingly, a functional nuclear localization signal was identified in the N-terminal region of BUFFY and in the absence of the MA, BUFFY accumulated in the nucleus. The functional implications of these findings are discussed.

Amino Acid Sequence↗

PubMed2005

Subcellular localization of the Triple Gene Block movement proteins of Beet necrotic yellow vein virus by electron microscopy.

The Triple Gene Block proteins TGBp1, TGBp2, and TGBp3 of Beet necrotic yellow vein virus (BNYVV) are required for efficient cell-to-cell spread of the infection. The TGB proteins can drive cell-to-cell movement of BNYVV in trans when expressed from a co-inoculated BNYVV RNA 3-based 'replicon'. TGBp2 and TGBp3 expressed from the replicon were nonfunctional in this assay if they were fused to the green fluorescent protein (GFP), but addition of a hemagglutinin (HA) tag to their C-termini did not incapacitate movement. Immunogold labeling of ultrathin sections treated with HA-specific antibodies localized TGBp2-HA and TGBp3-HA to what are probably structurally modified plasmodesmata (Pd) in infected cells. A similar subcellular localization was observed for TGBp1. Large gold-decorated membrane-rich bodies containing what appear to be short fragments of endoplasmic reticulum were observed near the cell periphery. The modified gold-decorated Pd and the membrane-rich bodies were not observed when the TGB proteins were produced individually in infections using the Tobacco mosaic virus P30 protein to drive cell-to-cell movement, indicating that these modifications are specific for TGB-mediated movement.

Beta vulgaris↗

PubMed1972

Subcellular Localization of Zinc and Calcium in Bean (Phaseolus vulgaris L.) Tissues.

Two bean (Phaseolus vulgaris L.) cultivars differing in growth responses to zinc were examined for differences in uptake and subcellular localization of (65)Zn during a 15-day growth period. The zinc-sensitive cultivar Sanilac showed initially a much higher rate of absorption, which declined after 24 hours. The zinc-tolerant cultivar Saginaw showed a slow but steady rate of absorption for 10 days. In roots as well as in stem callus tissues of both cultivars, three-fourths of the absorbed (65)Zn was localized in the "cytoplasmic" supernatant fractions (containing ribosomes and vacuolar sap). Very little (less than 7%) (65)Zn was localized in the cell wall fraction. There was a much greater proportion of the absorbed (65)Zn localized in root mitochondria and nuclei of the zinc-sensitive Sanilac than in the zinc-tolerant Saginaw. Stem callus tissues, however, did not show such cultivar differences in zinc accumulation at the sub-cellular level.Calcium-45 distribution in the cultivar Redkote showed preferential affinity for cell walls both in roots and stem cellus tissue. The percentage of absorbed (45)Ca associated with cell wall fractions of roots gradually increased with a corresponding decline in the percentage of radioactivity associated with the cytoplasmic fraction. At 15 days, 57% of the total (45)Ca in the roots was localized in the cell walls. A similar, albeit less pronounced, preferential (45)Ca sorption on cell walls occurred for the callus tissue. Calcium-45 also accumulated at later stages in the nuclear fraction, but there was no mitochondrial accumulation.

Journal Article↗

PubMedDate not supplied

Light-modulated subcellular localization of the alpha-subunit of GTP-binding protein Gq in crayfish photoreceptors.

Gq-type GTP-binding protein (Gq) plays an important role in invertebrate visual phototransduction. The subcellular localization of the alpha subunit of visual Gq in crayfish photoreceptor was investigated immunocytochemically and biochemically to demonstrate the details of the rhodopsin-Gq interaction. The localization of Gq(alpha) changed depending on the light condition. In the dark, Gq(alpha) was localized in the whole rhabdoms as the membrane-bound form. In the light, half of the Gq(alpha) was localized in the cytoplasm as the soluble form. The translocation of Gq(alpha) was reversible. The light-modulated translocation possibly controls the amount of Gq that can be activated by rhodopsin. In vitro hydroxylamine treatment of rhabdomeric membranes suggested that the translocation was regulated by the fatty-acid modification of Gq(alpha).

Adaptation, Ocular↗

PubMed2002

Expression and subcellular localization of NRAMP1 in human neutrophil granules.

Mutations at the Nramp1 gene cause susceptibility to infections with intracellular pathogens. In human blood, polymorphonuclear (PMN) leukocytes are the most abundant site of NRAMP1 messenger RNA (mRNA) expression, suggesting that NRAMP1 plays an important role in the activity of these cells. By Northern blot analysis, NRAMP1 mRNA was only detected in most mature neutrophils from bone marrow (band and segmented cells). A high-affinity polyclonal rabbit antihuman NRAMP1 antibody directed against the amino terminus of the protein was produced and used to study cellular and subcellular localization of the protein in primary human neutrophils. Subcellular fractionation of granule populations together with immunoblotting studies with granule-specific markers indicate that NRAMP1 expression is primarily in tertiary granules. These granules are positive for the matrix enzyme gelatinase and the membrane subunit of the vacuolar H(+)/ATPase and can be recruited for exocytosis by treatment of neutrophils with phorbol myristate acetate. Immunogold studies by cryoelectron microscopy with primary neutrophils confirm that a majority (75%) of NRAMP1-positive granules are also positive for gelatinase, but they also suggest further heterogeneity in this granule population. Presence of NRAMP1 in tertiary granules is in agreement with the late-stage appearance of NRAMP1 mRNA during neutrophil maturation in bone marrow. Finally, immunofluorescence studies of Candida albicans-containing phagosomes formed in neutrophils indicate that NRAMP1 is recruited from tertiary granules to the phagosomal membrane on phagocytosis, supporting a role for NRAMP1 in the antimicrobial defenses of human neutrophils.

Animals↗

PubMed2004

Direct binding of visual arrestin to microtubules determines the differential subcellular localization of its splice variants in rod photoreceptors.

Proper function of visual arrestin is indispensable for rapid signal shut-off in rod photoreceptors. Dramatic light-dependent changes in its subcellular localization are believed to play an important role in light adaptation of photoreceptor cells. Here we show that visual arrestin binds microtubules. The truncated splice variant of visual arrestin, p44, demonstrates dramatically higher affinity for microtubules than the full-length protein (p48). Enhanced microtubule binding of p44 underlies its earlier reported preferential localization to detergent-resistant membranes, where it is anchored via membrane-associated microtubules in a rhodopsin-independent fashion. Experiments with purified proteins demonstrate that arrestin interaction with microtubules is direct and does not require any additional protein partners. Most importantly, arrestin interactions with microtubules and light-activated phosphorylated rhodopsin are mutually exclusive, suggesting that microtubule interaction may play a role in keeping p44 arrestin away from rhodopsin in dark-adapted photoreceptors.

Alternative Splicing↗

PubMed1998

In situ subcellular localization of epitope-tagged human and rabbit carboxylesterases.

Carboxylesterases are a ubiquitous class of enzymes thought to be involved in xenobiotic metabolism and detoxification. Primary amino acid sequence data suggest that these proteins localize to the endoplasmic reticulum. However, since this family of proteins is highly homologous, the generation of specific reagents to monitor expression and subcellular localization has been unsuccessful. To accomplish in situ detection of a human alveolar macrophage carboxylesterase and a rabbit liver carboxylesterase, we constructed plasmids that expressed recombinant proteins containing an 11 amino acid influenza hemagglutinin tag near the C-terminus. These proteins retained carboxylesterase activity as determined by the conversion of o-nitrophenol acetate to o-nitrophenol. Following transfection of plasmids encoding these proteins into mammalian cells, cells were analyzed by both fluorescence and electron microscopy. The tagged enzymes were localized to the endoplasmic reticulum of both Cos7 monkey kidney cells and Rh30 human rhabdomyosarcoma cells. No tagged protein was detectable in the culture media. Hence, epitope tagging allowed the analysis of expression and localization of specific carboxylesterases. The methods described in this paper are, therefore, applicable to any protein, including those that are highly homologous to other candidate molecules.

Amino Acid Sequence↗

PubMed2004

Predicting subcellular localization of proteins by hybridizing functional domain composition and pseudo-amino acid composition.

Recent advances in large-scale genome sequencing have led to the rapid accumulation of amino acid sequences of proteins whose functions are unknown. Since the functions of these proteins are closely correlated with their subcellular localizations, many efforts have been made to develop a variety of methods for predicting protein subcellular location. In this study, based on the strategy by hybridizing the functional domain composition and the pseudo-amino acid composition (Cai and Chou [2003]: Biochem. Biophys. Res. Commun. 305:407-411), the Intimate Sorting Algorithm (ISort predictor) was developed for predicting the protein subcellular location. As a showcase, the same plant and non-plant protein datasets as investigated by the previous investigators were used for demonstration. The overall success rate by the jackknife test for the plant protein dataset was 85.4%, and that for the non-plant protein dataset 91.9%. These are so far the highest success rates achieved for the two datasets by following a rigorous cross validation test procedure, further confirming that such a hybrid approach may become a very useful high-throughput tool in the area of bioinformatics, proteomics, as well as molecular cell biology.

Algorithms↗

PubMed1992

Presence and subcellular localization of tyrosine aminotransferase and p-hydroxyphenyllactate dehydrogenase in epimastigotes of Trypanosoma cruzi.

Cell-free extracts of epimastigotes of Trypanosoma cruzi contain tyrosine aminotransferase (TAT) and p-hydroxyphenyllactate dehydrogenase (pHPLDH). The TAT activity could be separated from aspartate aminotransferase (ASAT) by polyacrylamide gel electrophoresis or DEAE-cellulose chromatography; the latter procedure also allowed complete separation of pHPLDH. The subcellular localization of both T. cruzi enzymes, as determined by digitonin extraction, subcellular fractionation by differential centrifugation, and isopycnic ultracentrifugation in sucrose gradients, was mainly cytosolic, with low mitochondrial activities.

Animals↗

PubMed1998

Subcellular localization of the US3 protein kinase of herpes simplex virus type 2.

One supposes that herpes simplex virus US3 gene product possessing serine/threonine protein kinase activity is a cytoplasmic enzyme. To determine its subcellular localization during viral replication we prepared an antiserum to a synthetic oligopeptide corresponding to the N-terminal region of the US3 protein of HSV type 2 strain 186. The US3 protein first appeared in the cytoplasm of infected cell at 4 h postinfection but strong fluorescence was detected in the nuclei at 8 h postinfection. At 12 h postinfection fluorescence was mainly detected in the cytoplasm, again. Further, the US3 protein expressed alone was widely distributed throughout the cell, indicating that the US3 protein by itself can be localized in the nuclei even in the absence of any other viral proteins. These observations suggest that the HSV-2 US3 protein kinase may function not only in the cytoplasm but also in the nuclei.

Amino Acid Sequence↗