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 361 records · Page 20Linked to original sources

PubMed2006

LOCATE: a mouse protein subcellular localization database.

We present here LOCATE, a curated, web-accessible database that houses data describing the membrane organization and subcellular localization of proteins from the FANTOM3 Isoform Protein Sequence set. Membrane organization is predicted by the high-throughput, computational pipeline MemO. The subcellular locations of selected proteins from this set were determined by a high-throughput, immunofluorescence-based assay and by manually reviewing >1700 peer-reviewed publications. LOCATE represents the first effort to catalogue the experimentally verified subcellular location and membrane organization of mammalian proteins using a high-throughput approach and provides localization data for approximately 40% of the mouse proteome. It is available at http://locate.imb.uq.edu.au.

Animals↗

PubMed1998

Changes in subcellular localization of metabotropic glutamate receptor subtypes during postnatal development of mouse thalamus.

High resolution immunoelectron microscopy was used to study subcellular localization patterns of three metabotropic glutamate receptor subtypes (mGluR1alpha, mGluR5, and mGluR2/3) during postnatal development of mouse ventral posterior (VP) thalamic nucleus. Immunoreactivity for all three mGluRs was detected from birth (postnatal day 0, P0), but mGluR1alpha showed dramatic changes in localization with age. In the first postnatal week, mGluR1alpha immunoreactivity was mainly found in proximal dendrites and somata and not usually associated with synaptic contacts. From the second postnatal week, it became concentrated in distal dendrites and preferentially associated with corticothalamic (RS) synapses. mGluR5 immunoreactivity was weaker than mGluR1alpha immunoreactivity at all postnatal ages and showed a similar change in subcellular distribution to that of mGluR1alpha. It was also localized in astrocytic processes. mGluR2/3 immunoreactivity was mainly localized in astrocytic processes surrounding neuronal somata and synapses and this pattern was consistently maintained through all postnatal ages. A small number of presynaptic axon terminals were labeled for mGluR2/3 immunoreactivity and formed asymmetrical synapses. This study demonstrates that Group I mGluR proteins (mGluR1alpha and mGluR5) become redistributed in association with the development of corticothalamic function as demonstrated physiologically, whereas Group II mGluR proteins (mGluR2/3) are mainly associated with neuroglia.

Aging↗

PubMed1983

Subcellular localization and tissue distribution of sialic acid precursor-forming enzymes.

The enzymes UDP-N-acetylglucosamine pyrophosphorylase, UDP-N-acetylglucosamine 2-epimerase, N-acetylmannosamine kinase, N-acetylglucosamine kinase and N-acetylglucosamine 2-epimerase, which are involved in the metabolism of N-acetylneuraminic acid, were studied in rat with regard to their subcellular localization and tissue distribution. The subcellular distribution studies in liver indicated that the enzymes are localized in the soluble cell fraction. In other tissues the comparison of enzyme activities in homogenates with that in high-speed supernatants led to a similar conclusion. UDP-N-acetylglucosamine pyrophosphorylase, N-acetylglucosamine kinase and N-acetylglucosamine 2-epimerase were detected in almost all tissues studied. UDP-N-acetylglucosamine 2-epimerase and N-acetylmannosamine kinase, two enzymes considered to be key enzymes in the N-acetylneuraminic acid biosynthesis, were detected only in sialoglycoprotein-secreting tissues, i.e. liver, salivary gland and intestinal mucosa. The low activity of the key enzymes in other tissues suggests that the biosynthetic pathway of N-acetylneuraminic acid is not the same in various tissues.

Animals↗

PubMed2005

Synaptic and subcellular localization of A-kinase anchoring protein 150 in rat hippocampal CA1 pyramidal cells: Co-localization with excitatory synaptic markers.

Excitatory and inhibitory ionotropic receptors are regulated by protein kinases and phosphatases, which are localized to specific subcellular locations by one of several anchoring proteins. One of these is the A-kinase anchoring protein (AKAP150), which confers spatial specificity to protein kinase A and protein phosphatase 2B in the rat brain. The distribution of AKAP150 was examined at rat hippocampal CA1 pyramidal cell asymmetric and symmetric post-synaptic densities and with respect to the distribution of markers of excitatory (vesicular glutamate transporter 1, glutamate receptor subunit 1) and inhibitory receptors (vesicular GABA transporter, GABA receptor type A beta2/3 subunits, gephyrin) and the Golgi marker, trans-Golgi network glycoprotein 38. AKAP150 was close to asymmetric synapses, consistent with numerous molecular and biochemical studies suggesting its interaction with components of the excitatory postsynaptic density. In contrast, we did not find AKAP150-immunoreactivity associated with inhibitory synapses in rat CA1 neurons, despite reports demonstrating an in vitro interaction between AKAP150 and GABA receptor type A receptor beta subunits, and the reported co-localization of these proteins in rat hippocampal cultures. There was some overlap between AKAP150 and GABA receptor type A receptor beta2/3-immunoreactivity intracellularly in perinuclear clusters. These findings support previous work indicating the integration of kinase and phosphatase activity at excitatory synapses by AKAP150, but do not support a role for selective targeting of AKAP150 and its accompanying proteins to inhibitory synapses.

A Kinase Anchor Proteins↗

PubMed1977

Subcellular localization of the alterations in phosphatidylinositol metabolism following glucose-induced insulin release from rat pancreatic islets.

The subcellular localization of the incorporation of 2-(3H)-myoinositol into lipids has been studied in isolated pancreatic islets of the rat. The recovery of lipid-bound myoinositol increased with time in the nuclear, mitochondrial, microsomal, and secretory granule fractions. The utilization of a filtration technique for the more complete separation of mitochondrial and secretory granule elements permitted us to show that the recovery of lipid-bound 2-(3H)-myoinositol increased most rapidly in the secretory granule fraction. A 30-minute exposure of prelabeled islets to a stimulatory concentration of D-glucose (3.0 mg./ml.) resulted in a statistically significant decrease in the amount of lipid-bound 2-(3H)-myoinositol that was recovered from the secretory granule fraction (p less than 0.001). In contrast, exposure of islets to the elevated glucose concentration had no statistically significant effect on the recovery of lipid-bound radioactivity from other subcellular fractions. Since the majority of lipid-bound radioactivity associated with the secretory granule fraction could be recovered with the presumptive secretory granule membranes, these data suggest that the hydrolysis of phosphatidylinositol that accompanies glucose-induced insulin secretion from the rat pancreatic islet may be localized to the beta granule and, in particular, to its limiting membrane.

Animals↗

PubMed1976

Esterolytic activities of rat intestinal mucosa. 1. Characterization, cellular distribution and subcellular localization of a glycerol-ester hydrolase.

The preferential cellular distribution in the villus tip and the subcellular localization in the endoplasmic reticulum of an intestinal glycerol-ester hydrolase from rat mucosa are described. The enzyme is shown not to be from either pancreatic or bacterial origin; it catalyzes the hydrolysis of short- and medium chain triglycerides and of p-nitrophenylacetate. Contrarily to the specificity found for the pig intestinal lipase (Serrero, Négrel and Ailhaud, 1975), no activity is detectable against acylCoA; a thiolester hydrolase different from the glycerol-ester hydrolase was demonstrated after differential solubilization and chromatographic separation. A high proportion of glycerol-ester hydrolase is present in the intestinal lumen; its possible complementary role in lipid degradation is discussed.

Aging↗

PubMed1998

Subcellular localization of Bacillus subtilis SMC, a protein involved in chromosome condensation and segregation.

We have investigated the subcellular localization of the SMC protein in the gram-positive bacterium Bacillus subtilis. Recent work has shown that SMC is required for chromosome condensation and faithful chromosome segregation during the B. subtilis cell cycle. Using antibodies against SMC and fluorescence microscopy, we have shown that SMC is associated with the chromosome but is also present in discrete foci near the poles of the cell. DNase treatment of permeabilized cells disrupted the association of SMC with the chromosome but not with the polar foci. The use of a truncated smc gene demonstrated that the C-terminal domain of the protein is required for chromosomal binding but not for the formation of polar foci. Regular arrays of SMC-containing foci were still present between nucleoids along the length of aseptate filaments generated by depleting cells of the cell division protein FtsZ, indicating that the formation of polar foci does not require the formation of septal structures. In slowly growing cells, which have only one or two chromosomes, SMC foci were principally observed early in the cell cycle, prior to or coincident with chromosome segregation. Cell cycle-dependent release of stored SMC from polar foci may mediate segregation by condensation of chromosomes.

Animals↗

PubMed1979

Freezing injury and phospholipid degradation in vivo in woody plant cells: I. Subcellular localization of phospholipase d in living bark tissues of the black locust tree (robinia pseudoacacia L.).

The subcellular localization of phospholipase D in homogenates of living bark tissues of the black locust tree (Robinia pseudoacacia L.) was examined and found in both soluble and particulate fractions. At least some of the soluble enzyme was considered to be compartmentalized in vacuoles. Considerable amounts of phospholipase D seemed to be tightly bound on several membranes such as endoplasmic reticulum, tonoplast, and a membrane associated with potassium-stimulated ATPase (pH 6.1). The mitochondrial fraction banding at the 40 to 43% (w/w) sucrose layer, however, had the lowest specific activity. The soluble and the particulate phospholipase D were considered to be similar in nature. It is possible that the particulate enzyme, as a part, may be derived from the coexisting nonvesiculated materials visualized in the electron micrograph of each membrane fraction. An involvement of the soluble or the presumed membrane-bound phospholipase D in phospholipid degradation in vivo during freezing at sublethal temperatures was discussed with special reference to freezing injury of plant cells.

Journal Article↗

PubMed1988

Different subcellular localization of neurotensin-receptor and neurotensin-acceptor sites in the rat brain dopaminergic system.

The subcellular localization of neurotensin-receptor sites (NT2 sites) and neurotensin-acceptor sites (NT1 sites) was studied in rat caudate-putamen by isopycnic centrifugation in sucrose density gradients. [3H]Neurotensin binding to NT2 sites occurred as a major peak at higher sucrose densities, colocalized with [3H]dopamine uptake, and as a small peak at a lower density; whereas binding to NT1 sites occurred as a single large peak at an intermediate density. 6-Hydroxydopamine lesions of the median forebrain bundle resulted in a total loss of NT2 sites in the caudate-putamen but did not affect NT2 sites in the nucleus accumbens and the olfactory tubercle. NT1 sites were not affected. Kainic acid injections into the rat caudate-putamen led to a partial decrease of NT1 sites in this region 5 days later. After a few weeks they returned to normal. Therefore NT2 sites are probably associated with presynaptic nigrostriatal dopaminergic terminals in the caudate-putamen but not in the nucleus accumbens and the olfactory tubercle. A possible association of NT1 sites with glial cells is suggested.

Animals↗

PubMed1981

Subcellular localization of the env-related glycoproteins in Friend erythroleukemia cells.

A scheme was developed for the subcellular fractionation of murine erythroleukemia cells transformed by Friend leukemia virus. The subcellular localization of the env-related glycoproteins was determined by immune precipitation with antiserum against gp70, the envelope glycoprotein of the helper virus, followed by gel electrophoresis. In cells labeled for 2 h with [35S]methionine, the glycoprotein encoded by the defective spleen focus-forming virus, gp55SFFV, was found primarily in the nuclear fraction and in fractions containing dense cytoplasmic membranes such as endoplasmic reticulum. A similar distribution was noted for gp85env, the precursor to gp70. The concentration of viral glycoproteins in the nuclear fraction could not be accounted for by contamination with endoplasmic reticulum. In pulse-chase experiments, neither glycoprotein underwent major redistribution. However, labeled gp85env disappeared from intracellular membranes with a half-time of 30 min to 1 h, whereas labeled gp55SFFV was stable during a 2-h chase. In plasma membrane preparations with very low levels of contamination with endoplasmic reticulum, gp70 was the major viral env-related glycoprotein detected; a minor amount of gp55SFFV and no gp85env could be detected. The unexpected result of these experiments is the amount of viral glycoproteins found in the nuclear fraction. Presence of viral proteins in the nucleus could be relevant to the mechanism of viral leukemogenesis.

Animals↗

PubMed1978

Subcellular localization of two long-chain acyl-coenzyme-A synthetases in Candida lipolytica.

Studies have been made on the subcellular localization of two long-chain acyl-coenzyme-A synthetases as well as glycerolphosphate acyltransferase and the acyl-CoA-oxidizing system in Candida lipolytica grown on oleic acid. Acyl-CoA synthetase I is distributed among different subcellular fractions, including microsomes and mitochondria where glycerolphosphate acyltransferase is located. On the other hand, acyl-CoA synthetase II is localized in microbodies where the acyl-CoA-oxidizing system is located. These results support our previous conclusion that acyl-CoA synthetase I is responsible for the production of acyl-CoA to be utilized for the synthesis of cellular lipids, while acyl-CoA synthetase II provides acyl-CoA that is exclusively degraded via beta-oxidation.

Candida↗

PubMedDate not supplied

Mechanism of uptake of technetium-tetrofosmin. I: Uptake into isolated adult rat ventricular myocytes and subcellular localization.

BACKGROUND: 99mTc-labeled tetrofosmin is a new myocardial imaging agent that gives stable heart uptake. However, little is known about the mechanism of uptake in heart tissue. METHODS AND RESULTS: Uptake of 99mTc-labeled tetrofosmin has been examined in isolated adult rat ventricular myocytes. The time course of uptake, efflux rate, and the effect of metabolic and cation channel inhibitors have been assessed. The subcellular localization of radioactivity in ex vivo rat heart tissue was examined by differential centrifugation of ventricular homogenate. Uptake into rat myocytes was found to be rapid and plateaued at approximately 1.5 pmol/10(6) cells/nmol extracellular Tc-labeled tetrofosmin after 60 minutes of incubation. Uptake was temperature dependent but independent of extracellular Tc-labeled tetrofosmin concentration. Uptake at 30 minutes was inhibited by the metabolic inhibitors iodoacetic acid acid and 2,4-dinitrophenol protein but was not affected by cation channel inhibitors. Cells previously incubated with 99mTc-labeled tetrofosmin and then placed into fresh medium were found to have a slow efflux of activity; after 1 hour, 65% of activity was still cell associated. The localization of radioactivity in subcellular fractions indicated that the majority of activity was recovered with the cytosol. However, examination of the distribution of two mitochondrial enzymes indicated that this may have been artifactual. Use of carbonyl cyanide m-chlorophenyl-hydrazone or oligomycin to perturb mitochondrial membrane potential decreased or increased recovery in the mitochondrial fraction, respectively. CONCLUSIONS: 99mTc-labeled tetrofosmin uptake by myocytes is by a metabolism-dependent process that does not involve cation channel transport. The most likely mechanism for this is by potential driven diffusion of the lipophilic cation across the sarcolemmal and mitochondrial membranes.

Animals↗

PubMed2000

Subcellular localization of epidermal growth factor in human submandibular gland.

Epidermal growth factor in human submandibular gland was localized at the subcellular level by means of an immunogold staining method. Labelling was observed in serous acini and ducts. In the acini, gold particles were found within secretory granules, indicating that the growth factor is released into the saliva through granule exocytosis. In the ductal system, the most intense reactivity was revealed in the principal cells of striated ducts. In these cells, an abundant population of small cytoplasmic vesicles was specifically stained. Immunoreactive vesicles were found both apically and basally, suggesting that ductal cells can release their products not only into the saliva but also into the interstitium.

Adolescent↗

PubMed1999

Alternative splicing regulates the subcellular localization of A-kinase anchoring protein 18 isoforms.

The cAMP-dependent protein kinase (PKA) is localized to specific subcellular compartments by association with A-kinase anchoring proteins (AKAPs). AKAPs are a family of functionally related proteins that bind the regulatory (R) subunit of PKA with high affinity and target the kinase to specific subcellular organelles. Recently, AKAP18, a low molecular weight plasma membrane AKAP that facilitates PKA-mediated phosphorylation of the L-type Ca(2+) channel, was cloned. We now report the cloning of two additional isoforms of AKAP18, which we have designated AKAP18beta and AKAP18gamma, that arise from alternative mRNA splicing. The AKAP18 isoforms share a common R subunit binding site, but have distinct targeting domains. The original AKAP18 (renamed AKAP18alpha) and AKAP18beta target the plasma membrane when expressed in HEK-293 cells, while AKAP18gamma is cytosolic. When expressed in epithelial cells, AKAP18alpha is targeted to lateral membranes, whereas AKAP18beta is accumulated at the apical membrane. A 23-amino acid insert, following the plasma membrane targeting domain, facilitates the association of AKAP18beta with the apical membrane. The data suggest that AKAP18 isoforms are differentially targeted to modulate distinct intracellular signaling events. Furthermore, the data suggest that plasma membrane AKAPs may be targeted to subdomains of the cell surface, adding additional specificity in intracellular signaling.

A Kinase Anchor Proteins↗

PubMed2004

Identification and subcellular localization of two solanesyl diphosphate synthases from Arabidopsis thaliana.

Two solanesyl diphosphate synthases, designated SPS1 and SPS2, which are responsible for the synthesis of the isoprenoid side chain of either plastoquinone or ubiquinone in Arabidopsis thaliana, were identified. Heterologous expression of either SPS1 or SPS2 allowed the generation of UQ-9 in a decaprenyl diphosphate synthase-defective strain of fission yeast and also in wild-type Escherichia coli. SPS1-GFP was found to localize in the ER while SPS2-GFP localized in the plastid of tobacco BY-2 cells. These two different subcellular localizations are thought to be the reflection of their roles in solanesyl diphosphate synthesis in two different parts: presumably SPS1 and SPS2 for the side chains of ubiquinone and plastoquinone, respectively.

Alkyl and Aryl Transferases↗

PubMed2001

Subcellular localization of bilirubin in rat brain after in vivo i.v. administration of [3H]bilirubin.

Bilirubin appears to be toxic in vitro to several cellular functions localized to different subcellular compartments. It would therefore be useful to know what concentrations of bilirubin might be found in cell organelles in vivo. Rats were anesthetized and allocated to one of three groups: control, hypercarbia, and hyperosmolality. Each rat received a 5-min bolus dose of bilirubin 50 mg/kg i.v. (containing approximately 200 microCi [(3)H]bilirubin). Rats were killed 10 or 30 min after the start of the bilirubin infusion. Each brain was homogenized, and subcellular fractions were isolated by high-speed gradient centrifugation in sucrose media. The gradients were separated into aliquots of 2 mL, and the protein content was determined in each aliquot. Radioactivity was determined by scintillation counting, and the content of bilirubin per milligram of protein was calculated. Statistical comparisons were performed with Kruskal-Wallis nonparametric ANOVA. There were highly significant differences in bilirubin content per milligram of protein among subcellular compartments in all groups and at both time points. In all groups there were relatively high concentrations of bilirubin in the myelin fraction, an interesting observation in light of the theory that membranes are the primary target of bilirubin toxicity. The very high concentration of bilirubin relative to protein in cytoplasm, ribosomes, and mitochondria in the hyperosmolar group are also notable in light of data from hyperbilirubinemic animals in which changes in electrophysiology or energy metabolism only appeared after hyperosmolar opening of the blood-brain barrier. The present data may be useful in planning in vitro studies of bilirubin toxicity in cell organelles.

Animals↗

PubMed1988

Ion microscopy: a new approach for subcellular localization of labelled molecules.

Secondary ion mass spectroscopy (SIMS) was used to obtain images representing the intracellular distribution of molecules labelled with carbon 14. Deoxyadenosine labelled with carbon 14 was added to a cultured human fibroblast cell medium, and the intracellular distribution of this molecule was studied using three different SIMS instruments: the CAMECA IMS 3F and SMI 300 ion microscopes and the UC-HRL scanning ion microprobe. Carbon 14 distribution images obtained by this method show that deoxyadenosine U-C14 is present in the cytoplasm as well as the nucleus, with a higher concentration in the nucleoli. Our study clearly demonstrates that ion microscopy is well suited for carbon 14 detection and localization at the subcellular level, permitting a wide variety of microanalytical tracer experiments.

Adult↗

PubMed2001

Subcellular localization of angiotensin II in kidney and adrenal.

OBJECTIVES: To investigate whether tissue angiotensin II generation occurs intra- or extracellularly, we studied the subcellular localization of angiotensin II in kidney and adrenal, two organs with high endogenous angiotensin II concentrations. DESIGN AND METHODS: Tissues were obtained, following a 1 h infusion of 125I-angiotensin I or 125I-angiotensin II to simultaneously determine the localization of plasma-derived angiotensin II, from five control pigs and four pigs that had been pretreated with the AT1 receptor antagonist eprosartan. Subcellular organelles, prepared by differential centrifugation from homogenized tissue, were characterized using organelle-specific markers. RESULTS: 125I-angiotensin II and angiotensin II were present in all organelles, with identical distribution profiles. In mitochondria-enriched fractions the relative specific activities [RSAs = (concentration per mg protein in fraction)/(concentration per mg protein in homogenate)] of the two peptides were similar to those in homogenate, whereas in cytosol-enriched fractions their RSAs were five- to 10-fold lower (P< 0.05 versus homogenate). In microsome- as well as in lysosome-enriched fractions the RSAs of 125I-angiotensin II and angiotensin II were two- to four-fold higher than in homogenate (P < 0.05), and their RSAs were also higher in renal nuclei-enriched fractions (P< 0.05). Eprosartan increased plasma angiotensin II to a larger degree than tissue angiotensin II and greatly reduced tissue 125I-angiotensin II. This led to similar decreases in the tissue/plasma concentration ratios of 125I-angiotensin II and angiotensin II. The subcellular distribution of both angiotensin II peptides was not affected by eprosartan. CONCLUSIONS: Local angiotensin II synthesis in adrenal and kidney occurs predominantly extracellularly, and is followed by rapid AT1 receptor-mediated endocytosis, thereby leading to high intracellular angiotensin II levels.

Acrylates↗