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Results for “Subcellular localization”

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PubMed1989

Quantitation and subcellular localization of proliferating cell nuclear antigen (PCNA/cyclin) in oocytes and eggs of Xenopus laevis.

Proliferating cell nuclear antigen (PCNA/cyclin) is a 36-kDa polypeptide present in the nuclei of mitotically active cells. It is known to be involved in DNA replication through an association with DNA polymerase delta. We examined the total content as well as the subcellular distribution of PCNA in the oocyte and the egg of Xenopus laevis by employing immunocytological staining and immunoblot analysis. While oocytes are not capable of replicating chromosomes, PCNA is abundant in the nucleus (about 65 ng per nucleus). The oocyte cytoplasm, on the other hand, does not contain a significant quantity of this protein. The amount of total PCNA does not change appreciably during oocyte maturation and the subsequent stages of egg cleavage. Thus, PCNA belongs to a class of proteins which are stockpiled during oogenesis in order to be utilized later for early embryogenesis.

Animals↗

PubMed2002

Primary structure of a dynamin-related mouse mitochondrial GTPase and its distribution in brain, subcellular localization, and effect on mitochondrial morphology.

A new member of the dynamin GTPase family (OPA1) was recently identified in humans and shown to be mutated in patients with dominant optic atrophy. To understand better the function of mammalian OPA1, we isolated a mouse ortholog (mOPA1) from brain and raised a specific antibody against its C terminus. The subcellular distribution of mOPA1 overexpressed in COS-7 cells largely overlapped that of endogenous cytochrome c, a well known mitochondrial marker, and dramatically affected mitochondrial morphology, altering it from tubular to vesicular. Mitochondrial targeting was mediated by the N-terminal region of mOPA1 as follows: deletion of the 124 N-terminal amino acids eliminated mitochondrial targeting, although fusion of the N-terminal 60 or 90 amino acids of mOPA1 with green fluorescent protein resulted in its mitochondrial targeting. mOPA1 was expressed widely in the mouse brain, especially in neurons of olfactory bulb, cerebral cortex, piriform cortex, hypothalamus, hippocampus, red nucleus, cochlear nucleus, motor trigeminal nucleus, facial nucleus, cerebellar nucleus, and Purkinje cells. Within dissociated cerebellar cells, mOPA1 protein was clearly observed in the dendrites and somas of neuronal cells, as well as in astrocytes and meningeal cells. In each case, it was distributed in the vesicular pattern seen in other cell types.

Amino Acid Sequence↗

PubMed2005

Subcellular localization of Apaf-1 in apoptotic rat pituitary cells.

A key step in the intrinsic apoptotic pathway is the assembly of the apoptosome complex. The apoptosome components are well known; however, the physiology of the assembly of the apoptosome complex at the cellular level is still poorly defined. The aim of this work was to study the subcellular distribution of the apoptosome scaffold protein apoptotic protease-activating factor 1 (Apaf-1) before and after triggering apoptosis in single somatotrophs. Somatotrophs are the subject of extensive pituitary tissue remodeling in different physiological situations in which the quality and the number of pituitary cells are determined by cell proliferation and apoptosis. We show herein that 2 h after triggering apoptosis with rotenone, Apaf-1 redistributed to the proximity of mitochondria. In addition, the degree of colocalization between Apaf-1 and fluorescently labeled caspase-9 significantly increased during the same period. Furthermore, we show herein for the first time in single cells that the colocalization between Apaf-1 and cytochrome c increases only transiently, indicating a transient interaction between cytochrome c and Apaf-1 during the activation of apoptosis in these cells.

Animals↗

PubMedDate not supplied

Expression and subcellular localization of dystrophin in skeletal, cardiac and smooth muscles during the human development.

Dystrophin, the product of the DMD gene, is present in all muscle types in normal individuals. Its function has yet to be elucidated, but its absence or the presence of a truncated version of the protein is responsible for the appearance of Duchenne and Becker muscular dystrophies. Using monoclonal antibodies raised against distinct regions of the dystrophin protein, we have examined its expression and subcellular distribution during the human development in skeletal and smooth muscles. We show that both dystrophin expression and its association to the plasma membrane take place earlier in cardiac and smooth muscles (8 weeks of gestation) than in skeletal muscle. In skeletal muscle, dystrophin is first detected in the cytoplasm, and progressively localizes to the plasma membrane from 10 weeks onwards. Since we have obtained marked differences in staining when using antibodies against either a central region of the protein or the C-terminal part, we suggest that different fetal and adult dystrophin isoforms are expressed, probably differing in their C-terminal domain. These findings are discussed in the context of the pathology of Duchenne muscular dystrophy.

Adult↗

PubMed2002

Combinatorial expression of TRPV channel proteins defines their sensory functions and subcellular localization in C. elegans neurons.

C. elegans OSM-9 is a TRPV channel protein involved in sensory transduction and adaptation. Here, we show that distinct sensory functions arise from different combinations of OSM-9 and related OCR TRPV proteins. Both OSM-9 and OCR-2 are essential for several forms of sensory transduction, including olfaction, osmosensation, mechanosensation, and chemosensation. In neurons that express both OSM-9 and OCR-2, tagged OCR-2 and OSM-9 proteins reside in sensory cilia and promote each other's localization to cilia. In neurons that express only OSM-9, tagged OSM-9 protein resides in the cell body and acts in sensory adaptation rather than sensory transduction. Thus, alternative combinations of TRPV proteins may direct different functions in distinct subcellular locations. Animals expressing the mammalian TRPV1 (VR1) channel in ASH nociceptor neurons avoid the TRPV1 ligand capsaicin, allowing selective, drug-inducible activation of a specific behavior.

Amino Acid Sequence↗

PubMed1992

Subcellular localization of recombinant truncated Gag precursor proteins of HIV expressed in Saccharomyces cerevisiae.

OBJECTIVE: To determine signals contained in the HIV-1 Gag precursor implicated in protein transport. DESIGN: To study the localization of truncated Gag proteins expressed in Saccharomyces cerevisiae. METHODS: Thin-section immunoelectron microscopy studies were performed on S. cerevisiae cells producing myristoylated or non-myristoylated Pr55gag, the core protein (p24) and several truncated Gag proteins. RESULTS: Pr55gag and the carboxy-terminal truncated Gag proteins were myristoylated and localized at the plasma membrane. p24 was localized in the nucleus or perinuclear membrane. However, addition of a myristoyl group to p24 targeted this molecule to the plasma membrane. CONCLUSIONS: The myristoylated amino-terminal 214 amino acids are sufficient to target Pr55gag to the plasma membrane. Subcellular signals implicated in protein transport are present in the core p24 polypeptide which may become dominant or accessible in the absence of the amino-myristoyl group.

Base Sequence↗

PubMed1987

Subcellular localization and kinetic properties of arginase from the liver of Genypterus maculatus.

1. From the liver of the teleost fish Genypterus maculatus, a partially purified preparation of arginase was obtained and characterized. 2. The Km value for arginine was found to be 9.1 mM at pH 7.5 and 11.5 mM at the optimum pH of 9.5. At both pH values, competitive inhibition was caused by ornithine and lysine, whereas proline, leucine, valine and isoleucine caused a non-competitive inhibitory effect. Branched chain amino acids were more inhibitory than proline. 3. The enzyme was found localized in the mitochondrial matrix of the liver of Genypterus maculatus. It is suggested that this localization would be of importance in the use of arginine as an energy source.

Animals↗

PubMed2001

Assessment of the subcellular localization of the herpes simplex virus structural protein VP22 in the absence of other viral gene products.

We previously demonstrated that the herpes simplex virus type 1 (HSV-1) structural protein VP22 exists in the cytoplasm early in infection and migrates to and accumulates in the nucleus late in infection (J. Virol. 73(8) (1999) 6769). The goal of this study is to document the behavior of VP22 in cells in the absence of other viral polypeptides. We characterized the effects of various indirect immunofluorescence sample preparation conditions on the localization of VP22 in cells and have determined the following. (i) Fixing with formaldehyde and permeabilizing with acetone maintains the structure of microtubules in cells, in as much as we observed classic microtubule organizing centers. (ii) Acetone or methanol alone did not completely fix the cells. (iii) Triton X-100 decreased tubulin immunofluorescence signals in our system. (iv) VP22 predominated in the nucleus of cells that were fixed with formaldehyde. Based on our results, we conclude the following. (v) Due to the partial fixation by acetone or methanol alone, microtubules form diffuse irregular shapes. (vi) VP22 is detected in the cytoplasm of cells fixed with acetone or methanol only due to its seepage from the nucleus. Taken together, these findings indicate that (vii) the nuclear localization of VP22 does not require additional viral factors.

Animals↗

PubMed2003

Alternative splicing controls myotonic dystrophy protein kinase structure, enzymatic activity, and subcellular localization.

Transcripts of the myotonic dystrophy protein kinase (DMPK) gene, a member of the Rho kinase family, are subject to cell-type specific alternative splicing. An imbalance in the splice isoform profile of DMPK may play a role in the pathogenesis of DM1, a severe multisystemic disorder. Here, we report how structural subdomains determine biochemical properties and subcellular distribution of DMPK isoforms. A newly developed kinase assay revealed that DMPK is a Lys/Arg-directed kinase. Individual DMPK isoforms displayed comparable transphosphorylation activity and sequence preference for peptide substrates. However, DMPK autophosphorylation and phosphorylation of MYPT1 (as putative in vivo target of DMPK), were dependent on presence of an alternatively spliced VSGGG motif and the nature of the C terminus. In-gel effects of the VSGGG motif on the migration behavior of full-length kinase provide evidence for a model in which this motif mediates 3-D-conformational changes in DMPK isoforms. Finally, different C termini endow DMPK with the ability to bind to either endoplasmic reticulum or mitochondria or to adopt a cytosolic location. Our results suggest that DMPK isoforms have cell-type and location dependent substrate specificities with a role in organellar and cytoarchitectural dynamics.

Alternative Splicing↗

PubMed1980