scholarly journals Expression and Differential Intracellular Localization of Two Major Forms of Human 8-Oxoguanine DNA Glycosylase Encoded by Alternatively Spliced OGG1 mRNAs

1999 ◽  
Vol 10 (5) ◽  
pp. 1637-1652 ◽  
Author(s):  
Kenichi Nishioka ◽  
Toshio Ohtsubo ◽  
Hisanobu Oda ◽  
Toshiyuki Fujiwara ◽  
Dongchon Kang ◽  
...  
Keyword(s):  
Intracellular Localization ◽  
Nuclear Extract ◽  
Dna Glycosylase ◽  
Mitochondrial Targeting ◽  
Electron Microscopic ◽  
C Terminus ◽  
Alternatively Spliced ◽  
Targeting Signal ◽  
Processed Form

We identified seven alternatively spliced forms of human 8-oxoguanine DNA glycosylase (OGG1) mRNAs, classified into two types based on their last exons (type 1 with exon 7: 1a and 1b; type 2 with exon 8: 2a to 2e). Types 1a and 2a mRNAs are major in human tissues. Seven mRNAs are expected to encode different polypeptides (OGG1–1a to 2e) that share their N terminus with the common mitochondrial targeting signal, and each possesses a unique C terminus. A 36-kDa polypeptide, corresponding to OGG1–1a recognized only by antibodies against the region containing helix-hairpin-helix-PVD motif, was copurified from the nuclear extract with an activity introducing a nick into DNA containing 8-oxoguanine. A 40-kDa polypeptide corresponding to a processed form of OGG1–2a was detected in their mitochondria using antibodies against its C terminus. Electron microscopic immunocytochemistry and subfractionation of the mitochondria revealed that OGG1–2a locates on the inner membrane of mitochondria. Deletion mutant analyses revealed that the unique C terminus of OGG1–2a and its mitochondrial targeting signal are essential for mitochondrial localization and that nuclear localization of OGG1–1a depends on the NLS at its C terminus.

The alternatively spliced exon of the platelet-derived growth factor A chain encodes a nuclear targeting signal

1989 ◽  
Vol 9 (5) ◽  
pp. 2251-2253
Author(s):  
D W Maher ◽  
B A Lee ◽  
D J Donoghue
Keyword(s):  
Growth Factor ◽  
Dihydrofolate Reductase ◽  
Platelet Derived Growth Factor ◽  
Nuclear Targeting ◽  
Factor B ◽  
Cytoplasmic Proteins ◽  
C Terminus ◽  
Alternatively Spliced ◽  
Targeting Signal ◽  
A Chain

We have previously shown that the SIS/platelet-derived growth factor B chain contains a nuclear targeting signal near its C terminus. Here we show that the platelet-derived growth factor A chain also contains a nuclear targeting signal encoded by an exon which is subject to alternative splicing. This sequence is capable of targeting a nonsecreted form of the A chain to the nucleus and can also target the cytoplasmic proteins dihydrofolate reductase, chloramphenicol acetyltransferase, and pyruvate kinase to the nucleus.

scholarly journals Allostery between two binding sites in the ion channel subunit TRIP8b confers binding specificity to HCN channels

2017 ◽  
Vol 292 (43) ◽  
pp. 17718-17730 ◽  
Author(s):  
Kyle A. Lyman ◽  
Ye Han ◽  
Robert J. Heuermann ◽  
Xiangying Cheng ◽  
Jonathan E. Kurz ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Cyclic Nucleotide ◽  
Tetratricopeptide Repeat ◽  
Hcn Channels ◽  
Protein Protein Interactions ◽  
C Terminus ◽  
Peroxisomal Targeting ◽  
Targeting Signal ◽  
Peroxisomal Targeting Signal

Tetratricopeptide repeat (TPR) domains are ubiquitous structural motifs that mediate protein–protein interactions. For example, the TPR domains in the peroxisomal import receptor PEX5 enable binding to a range of type 1 peroxisomal targeting signal motifs. A homolog of PEX5, tetratricopeptide repeat–containing Rab8b-interacting protein (TRIP8b), binds to and functions as an auxiliary subunit of hyperpolarization-activated cyclic nucleotide (HCN)–gated channels. Given the similarity between TRIP8b and PEX5, this difference in function raises the question of what mechanism accounts for their binding specificity. In this report, we found that the cyclic nucleotide–binding domain and the C terminus of the HCN channel are critical for conferring specificity to TRIP8b binding. We show that TRIP8b binds the HCN cyclic nucleotide–binding domain through a 37-residue domain and the HCN C terminus through the TPR domains. Using a combination of fluorescence polarization– and co-immunoprecipitation–based assays, we establish that binding at either site increases affinity at the other. Thus, allosteric coupling of the TRIP8b TPR domains both promotes binding to HCN channels and limits binding to type 1 peroxisomal targeting signal substrates. These results raise the possibility that other TPR domains may be similarly influenced by allosteric mechanisms as a general feature of protein–protein interactions.

scholarly journals Human peroxisomal l-alanine: glyoxylate aminotransferase. Evolutionary loss of a mitochondrial targeting signal by point mutation of the initiation codon

1990 ◽  
Vol 268 (2) ◽  
pp. 517-520 ◽  
Author(s):  
Y Takada ◽  
N Kaneko ◽  
H Esumi ◽  
P E Purdue ◽  
C J Danpure
Keyword(s):  
Point Mutation ◽  
Signal Sequence ◽  
Primary Hyperoxaluria ◽  
Initiation Codon ◽  
Mitochondrial Targeting ◽  
Primary Hyperoxaluria Type 1 ◽  
Targeting Signal ◽  
Glyoxylate Aminotransferase ◽  
Hyperoxaluria Type

The amino acid sequence of human hepatic peroxisomal L-alanine: glyoxylate aminotransferase 1 (AGTI) deduced from cDNA shows 78% sequence identity with that of rat mitochondrial AGTI, but lacks the N-terminal 22 amino acids (the putative mitochondrial targeting signal). In humans this signal appears to have been deleted during evolution by a point mutation of the initiation codon ATG to ATA. These data suggest that the targeting defect in primary hyperoxaluria type 1, in which AGT1 is diverted from the peroxisomes to the mitochondria, could be due to a point mutation that reintroduces all or part of the mitochondrial signal sequence.

scholarly journals The alternatively spliced exon of the platelet-derived growth factor A chain encodes a nuclear targeting signal.

1989 ◽  
Vol 9 (5) ◽  
pp. 2251-2253 ◽  
Author(s):  
D W Maher ◽  
B A Lee ◽  
D J Donoghue
Keyword(s):  
Growth Factor ◽  
Dihydrofolate Reductase ◽  
Platelet Derived Growth Factor ◽  
Nuclear Targeting ◽  
Factor B ◽  
Cytoplasmic Proteins ◽  
C Terminus ◽  
Alternatively Spliced ◽  
Targeting Signal ◽  
A Chain

We have previously shown that the SIS/platelet-derived growth factor B chain contains a nuclear targeting signal near its C terminus. Here we show that the platelet-derived growth factor A chain also contains a nuclear targeting signal encoded by an exon which is subject to alternative splicing. This sequence is capable of targeting a nonsecreted form of the A chain to the nucleus and can also target the cytoplasmic proteins dihydrofolate reductase, chloramphenicol acetyltransferase, and pyruvate kinase to the nucleus.

scholarly journals TNNI1 Mutated in Autosomal Dominant Proximal Arthrogryposis

2021 ◽  
Vol 8 (1) ◽  
pp. e649
Author(s):  
Yukako Nishimori ◽  
Aritoshi Iida ◽  
Masashi Ogasawara ◽  
Mariko Okubo ◽  
Yuki Yonenobu ◽  
...  
Keyword(s):  
Autosomal Dominant ◽  
Genomic Analysis ◽  
Microscopic Analysis ◽  
Electron Microscopic ◽  
Japanese Family ◽  
Genetic Studies ◽  
C Terminus ◽  
The Family

ObjectivesThe main objective of this case report is to identify a gene associated with a Japanese family with autosomal dominant arthrogryposis.MethodsWe performed clinicopathologic diagnosis and genomic analysis using trio-based exome sequencing.ResultsA 14-year-old boy had contractures in the proximal joints, and the serum creatine kinase level was elevated. Muscle biopsy demonstrated a moth-eaten appearance in some type 1 fibers, and electron microscopic analysis revealed that type 1 fibers had Z disk streaming. We identified a heterozygous nonsense variant, c.523A>T (p.K175*), in TNNI1 in the family.DiscussionThe altered amino acid residue is within the tropomyosin-binding site near the C-terminus, in a region homologous to the variational hotspot of Troponin I2 (TNNI2), which is associated with distal arthrogryposis type 1 and 2b. Compared with patients with TNNI2 variants, our patient had a milder phenotype and proximal arthrogryposis. We report here a case of proximal arthrogryposis associated with a TNNI1 nonsense variant, which expands the genetic and clinical spectrum of this disease. Further functional and genetic studies are required to clarify the role of TNNI1 in the disease.

scholarly journals maf1 mutation alters the subcellular localization of the Mod5 protein in yeast.

1994 ◽  
Vol 41 (4) ◽  
pp. 441-448 ◽  
Author(s):  
M Murawski ◽  
B Szcześniak ◽  
T Zoładek ◽  
A K Hopper ◽  
N C Martin ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Intracellular Localization ◽  
Trna Modification ◽  
Red Pigment ◽  
Mitochondrial Targeting ◽  
Cytosolic Protein ◽  
Initiation Of Translation ◽  
Intracellular Compartments ◽  
Targeting Signal ◽  
Modification Enzyme

Two forms of Mod5p, a tRNA modification enzyme, are found in three intracellular compartments, mitochondria, cytoplasm and nucleus, but are encoded by a single MOD5 gene. The two forms of the enzyme, Mod5p-I and Mod5p-II differ at the N-termini and are produced by initiation of translation at different start codons. Mod5p-I does contain a mitochondrial targeting signal and is distributed between mitochondria and cytoplasm, whereas Mod5p-II is found in the cytosol and nucleus (Boguta, M., et al. 1994, Mol. Cell. Biol. 14, 2298-2306). In the present work mutants which mislocalize the Mod5p-I enzyme were isolated. The screen was based on a correlation between the amount of cytosolic protein and the efficiency of tRNA mediated suppression. Identification of mutants is possible because a red pigment accumulates in the cells unable to suppress an ade2-1 nonsense allele. The maf1 mutant, with an altered intracellular localization of the Mod5p-I protein, was isolated. Immunofluorescence data suggest that the mutation causes mislocalization of the Mod5p-I to the nucleus.

scholarly journals Structural Determinants Critical for Localization and Signaling within the Seventh Transmembrane Domain of the Type 1 Corticotropin Releasing Hormone Receptor: Lessons from the Receptor Variant R1d

2008 ◽  
Vol 22 (11) ◽  
pp. 2505-2519 ◽  
Author(s):  
Danijela Markovic ◽  
Hendrik Lehnert ◽  
Michael A. Levine ◽  
Dimitris K. Grammatopoulos
Keyword(s):  
Plasma Membrane ◽  
Transmembrane Domain ◽  
Intracellular Localization ◽  
Receptor Expression ◽  
Site Directed Mutagenesis ◽  
Functional Responses ◽  
Membrane Expression ◽  
Recombinant Receptors ◽  
C Terminus

Abstract The type 1 CRH receptor (CRH-R1) plays a fundamental role in homeostatic adaptation to stressful stimuli. CRH-R1 gene activity is regulated through alternative splicing and generation of various CRH-R1 mRNA variants. One such variant is the CRH-R1d, which has 14 amino acids missing from the putative seventh transmembrane domain due to exon 13 deletion, a splicing event common to other members of the B1 family of G protein-coupled receptors. In this study, using overexpression of recombinant receptors in human embryonic kidney 293 and myometrial cells, we showed by confocal microscopy that in contrast to CRH-R1α, the R1d variant is primarily retained in the cytoplasm, although some cell membrane expression is also evident. Use of antibodies against the CRH-R1 C terminus in nonpermeabilized cells showed that membrane-expressed CRH-R1d contains an extracellular C terminus. Interestingly, treatment of CRH-R1d-expressing cells with CRH (100 nM) for 45–60 min elicited functional responses associated with a significant reduction of plasma membrane receptor expression, redistribution of intracellular receptors, and increased receptor degradation. Site-directed mutagenesis studies identified the cassette G356-F358 within transmembrane domain 7 as crucial for CRH-R1α stability to the plasma membrane because deletion of this cassette caused substantial intracellular localization of CRH-R1 α. Most importantly, coexpression studies between CRH-R1d and CRH-R2β demonstrated that the CRH-R2β could partially rescue CRH-R1d membrane expression, and this was associated with a significant attenuation of urocotrin II-induced cAMP production and ERK1/2 and p38MAPK activation, suggesting that CRH-R1d might specifically induce heterologous impairment of CRH-R2 signaling responses. This mechanism appears to involve accelerated CRH-R2β endocytosis.

The Morphology of the Rat Kidney Following Folic Acid Administration

1970 ◽  
Vol 28 ◽  
pp. 200-201
Author(s):  
Aline Byrnes ◽  
Elsa E. Ramos ◽  
Minoru Suzuki ◽  
E.D. Mayfield
Keyword(s):  
Folic Acid ◽  
De Novo ◽  
Specific Activity ◽  
Rat Kidney ◽  
Present Report ◽  
Intracellular Localization ◽  
Male Rats ◽  
Renal Hypertrophy ◽  
Electron Microscopic ◽  
Biochemical Alterations

Renal hypertrophy was induced in 100 g male rats by the injection of 250 mg folic acid (FA) dissolved in 0.3 M NaHCO3/kg body weight (i.v.). Preliminary studies of the biochemical alterations in ribonucleic acid (RNA) metabolism of the renal tissue have been reported recently (1). They are: RNA content and concentration, orotic acid-c14 incorporation into RNA and acid soluble nucleotide pool, intracellular localization of the newly synthesized RNA, and the specific activity of enzymes of the de novo pyrimidine biosynthesis pathway. The present report describes the light and electron microscopic observations in these animals. For light microscopy, kidney slices were fixed in formalin, embedded, sectioned, and stained with H & E and PAS.

The Immuno-Electron Microscopic Localization of the Mo-Fe Protein Component of Nitrogenase in Cells of Azotobacter Vinelandii

1973 ◽  
Vol 31 ◽  
pp. 574-575
Author(s):  
J. T. Stasny ◽  
R. C. Burns ◽  
R. W. F. Hardy
Keyword(s):  
Cellular Localization ◽  
Direct Evidence ◽  
Azotobacter Vinelandii ◽  
Intracellular Localization ◽  
Protein Component ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Fe Protein ◽  
Intracytoplasmic Membranes

Structure-functlon studies of biological N2-fixation have correlated the presence of the enzyme nitrogenase with increased numbers of intracytoplasmic membranes in Azotobacter. However no direct evidence has been provided for the internal cellular localization of any nitrogenase. Recent advances concerned with the crystallizatiorTand the electron microscopic characterization of the Mo-Fe protein component of Azotobacter nitrogenase, prompted the use of this purified protein to obtain antibodies (Ab) to be conjugated to electron dense markers for the intracellular localization of the protein by electron microscopy. The present study describes the use of ferritin conjugated to goat antitMo-Fe protein immunoglobulin (IgG) and the observations following its topical application to thin sections of N2-grown Azotobacter.

Electron Microscopic investigation of crooke’s change in the pituitaries of patients with hypercorticism

1989 ◽  
Vol 47 ◽  
pp. 848-849
Author(s):  
E. Horvath ◽  
K. Kovacs ◽  
L. Stefaneanu ◽  
N. Losinski
Keyword(s):  
Nucleolar Organizer ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Ectopic Acth Syndrome ◽  
Nucleolar Organizer Regions ◽  
Electron Microscopic ◽  
Human Pituitary ◽  
Ectopic Acth ◽  
Crooke’S Hyalinization

Human pituitary corticotropins have unique morphologic markers: bundles of type-1 filaments, measuring approximately 70 A in width and representing cytokeratin. The extreme ring-like accumulation of type-1 filaments, known as Crooke's hyalinization, signals functional suppression of the corticotropins and occurs in endogenous and exogenous glucocorticoid excess, caused by ACTH-secreting pituitary adenoma, glucocorticoid secreting adrenocortical tumor, ectopic ACTH-syndrome and administration of pharmacologic doses of glucocorticoids. Cells of autonomous corticotroph adenomas usually do not show Crooke's hyalin change. A minority of these tumors, however, retains sensitivity to the negative feed-back effect of elevated blood glucocorticoid levels and display typical Crooke’s change.In the present study pituitary corticotropins in various phases of Crooke's hyalinization were investigated in patients with glucocorticoid excess of various origin, applying histology, immunocytochemistry, count of argyrophilic nucleolar organizer regions (AgNOR), and transmission electron microscopy.

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