Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “truncation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 181 records · Page 10Linked to original sources
PubMed2001

Association behaviour of human betaB1-crystallin and its truncated forms.

betaB1-crystallin plays an important role in the assembly of betaH-crystallin yet is known to be subject to N-terminal sequence truncations during human lens development and ageing. Here we have over-expressed human betaB1-crystallin, and various truncated forms in Escherichia coli and used mass spectrometry to monitor the monomer molecular weight. Gel permeation chromatography and laser light scattering have been used to estimate the assembly size of the various polypeptides as a function of protein concentration. The full-length betaB1-crystallin behaves as a dimer, like recombinant human betaB2-crystallin, but undergoes further self-association at high protein concentrations, unlike the betaB2-crystallin. Major truncations from the N-terminal extension lead to anomalous behaviour on gel permeation chromatography indicative of altered interactions with the column matrix, whereas light scattering indicated dimers at low protein concentration that self-associate as a function of protein concentration. Loss of 41 residues from the N-terminus, equivalent to an in vivo truncation site, resulted in temperature-dependent phase separation behaviour of the shortened betaB1-crystallin. Good crystals have been grown of a truncated version of human betaB1-crystallin using an in vitro cleavage protocol.

Chromatography, Gel↗
PubMed2001

Link between truncated fractals and coupled oscillators in biological systems.

This article aims at providing a new theoretical insight into the fundamental question of the origin of truncated fractals in biological systems. It is well known that fractal geometry is one of the characteristics of living organisms. However, contrary to mathematical fractals which are self-similar at all scales, the biological fractals are truncated, i.e. their self-similarity extends at most over a few orders of magnitude of separation. We show that nonlinear coupled oscillators, modeling one of the basic features of biological systems, may generate truncated fractals: a truncated fractal pattern for basin boundaries appears in a simple mathematical model of two coupled nonlinear oscillators with weak dissipation. This fractal pattern can be considered as a particular hidden fractal property. At the level of sufficiently fine precision technique the truncated fractality acts as a simple structure, leading to predictability, but at a lower level of precision it is effectively fractal, limiting the predictability of the long-term behavior of biological systems. We point out to the generic nature of our result.

Animals↗
PubMed1998

The truncated form of the Epstein-Barr virus LMP-1 is dispensable or complimentable by the full-length form in virus infection and replication.

The Epstein-Barr virus (EBV) latent membrane protein-1 (LMP-1) gene of the Akata virus strain was cloned, and its nucleotide sequence was determined. Compared with the B95-8 strain, the translation initiation codon for the truncated LMP-1 gene, which is expressed in the lytic cycle, was lost. Immunoblotting showed that Akata EBV produces no truncated LMP-1 protein in any state and that the full-length LMP-1 protein is expressed at a significant level during lytic infection. The results suggest that the truncated LMP-1 protein is dispensable for EBV infection and replication or that the full-length form can "functionally" complement the truncated form if the truncated form has a function.

Base Sequence↗
PubMed1989

GLP-1 (glucagon-like peptide 1) and truncated GLP-1, fragments of human proglucagon, inhibit gastric acid secretion in humans.

Glucagon-like peptide 1 amide (GLP-1 amide), a predicted product of the glucagon gene (proglucagon 72-107-amide), and truncated GLP-1 (proglucagon 78-107-amide), recently isolated from porcine small intestine, were infused in doses of 100 and 400 ng/kg/hr and 12.5 and 50 ng/kg/hr, respectively, into eight volunteers to study pharmacokinetics and effects on pentagastrin-stimulated gastric acid secretion (plateau stimulation with pentagastrin at D50: 100 ng/kg/hr). The concentration of GLP-1 in plasma increased from 64 +/- 12 to 189 +/- 23 and 631 +/- 76 pmol/liter, respectively. The concentration of truncated GLP increased from approximately 7 pmol/liter to 28 +/- 3 pmol/liter during the high rate of infusion. A similar increase was seen in response to a mixed meal in eight normal volunteers. The metabolic clearance rate (MCR) of GLP-1 was 2.2 +/- 0.3 and 2.6 +/- 0.3 ml/kg/min, respectively, and the half-life in plasma was 17 +/- 2 min. The MCR of truncated GLP-1 was 13 +/- 2.8 ml/kg/min and the half-life 11.4 +/- 2.1 min. GLP-1 reduced the pentagastrin-stimulated acid secretion 16 +/- 9% during the low-rate infusion and 23 +/- 12% during the high rate (P less than 0.05). Truncated GLP-1 caused a 36 +/- 3% inhibition during the high infusion rate. Thus truncated GLP-1, a naturally occurring peptide, is a potent inhibitor of acid secretion in man and more so than GLP-1.

Adult↗
PubMed2004

Carboxyl terminus truncated human papillomavirus type 58 L1 protein maintains its bioactivity and ability to form virus-like particles.

To prepare carboxyl terminus truncated human papillomavirus type 58 L1 (HPV58L1) protein and evaluate its ability to form virus-like particles, the baculovirus and Sf-9 insect cells was used to express HPV58L1 protein, and pFastBac-Htb containing HPV58L1 gene sequence of carboxyl terminus truncation was generated. Then Sf-9 cells were infected with recombinant baculovirus. After being cultured, the post-infected cells expressing--HPV58L1 protein were harvested and analyzed by SDS-PAGE and Western blot. The ProBond purification system was used for protein purification. The bio-activity of purified protein was identified by mouse erythrocyte hemagglutination assay, and the VLP formation was examined with transmission electron microscope. Our results showed that the recombinant baculovirus was generated and the Sf-9 cells was infected with the recombinant baculovirus, and after collecting, total cellular proteins were extracted. Truncated HPV58L1 protein with MW 58KD was revealed by SDS-PAGE and confirmed by Western blot. The purified L1 proteins under native condition could cause mouse erythrocytes to agglutinate and form VLP. It is concluded that HPV58L1 protein with carboxyl terminus truncation could be efficiently expressed. In baculovirus Sf-9 cells expression system, the purified protein could self-assemble into virions in vitro, and induce agglutination of mouse erythrocytes, indicating that carboxyl terminus truncation does not interfere with the bioactivity of HPV58L1 protein.

Baculoviridae↗
PubMed2003

Evaluation of the diagnostic accuracy of the stop codon (SC) assay for identifying protein-truncating mutations in the BRCA1and BRCA2genes in familial breast cancer.

Screening for protein-truncating mutations of the BRCA1 and BRCA2 genes is useful in genetic testing for familial breast cancer because, first, the methods are usually simple and not expensive, and second, the detected mutations indicate pathogenic mutations in general. We evaluated the diagnostic accuracy of the stop codon (SC) assay for detecting protein-truncating mutations in the BRCA1 and BRCA2 genes by comparing the results with DNA sequencing in samples from 29 patients with breast cancer from 24 Japanese families with a history of breast cancer. Protein-truncating mutations were detected in 5 of the 24 families (20.8%; two in the BRCA1 gene and three in the BRCA2 gene). Among the 176 DNA fragments examined using the SC assay, the existence of three protein-truncating mutations (one in the BRCA1 gene and two in the BRCA2gene) was predicted correctly by the assay. Only one reverse transcriptase-polymerase chain reaction fragment was positive for the SC assay but was negative using DNA sequencing. Our study showed clearly that the SC assay is sensitive (3 of 3, 100%) and specific (172 of 173, 99%) for detecting pathogenic protein-truncating mutations in the BRCA1 and BRCA2 genes, and that it could be useful for screening larger populations.

Biological Assay↗
PubMed1992

Retained in vitro infectivity and cytopathogenicity of HIV-1 despite truncation of the C-terminal tail of the env gene product.

Five in-frame stop mutations in the HIV-1 env gene, which lead to the production of env gene products truncated within the cytoplasmic C-terminal tail, have been generated and their effects on membrane fusion capacity, glycoprotein incorporation into virus particles, infectivity, and cytopathogenicity were analyzed. The resulting truncated glycoproteins were processed normally, were transported to the cell surface, and were able to induce CD4-dependent membrane fusion. The membrane fusion capacity of one of the mutant glycoproteins with a truncation of 144 amino acids was increased to about double of that induced by wild-type glycoprotein. With a single exception, the truncated viral glycoproteins were incorporated into virus particles which were infectious and cytopathic for permissive MT-4 cells. The infection kinetics with the mutated viruses were, however, delayed to varying degrees in comparison to infection with wild-type virus. Nevertheless, in each case, PCR amplification and direct sequencing of viral DNA in the infected cultures confirmed the presence of the mutant and the absence of revertant DNA. The mutant virus encoding a viral glycoprotein with the longest truncation (144 amino acids), in which only 7 cytoplasmic C-terminal amino acids in gp41 remain, resulted in infection kinetics in MT-4 cells which were only marginally delayed in comparison to those induced by wild-type virus. This means that these C-terminal 144 amino acids of gp41 are not necessary for glycoprotein incorporation into virus particles nor do they significantly contribute to the infectivity nor the cytopathogenicity of HIV-1 in MT-4 cells.

Biological Transport, Active↗
PubMed1995

Characterization and quantification of full-length and truncated Na,K-ATPase alpha 1 and beta 1 RNA transcripts expressed in human retinal pigment epithelium.

We have characterized cDNA clones encoding the alpha 1 and beta 1 subunits of Na,K-ATPase produced in the human retinal pigment epithelium (hRPE). In addition to isolating clones corresponding to known sequences of Na,K-ATPase subunits, we report hitherto unknown forms of Na,K-ATPase with unique deduced amino acid (aa) sequences in their C-termini. Truncated cDNA sequences were found for both the beta 1 and alpha 1 subunits. While the beta 1 sequence is truncated by two aa residues at the C terminus, in the alpha 1 sequence 342 aa have been replaced by a unique sequence containing only 44 aa. Interestingly, this new C-terminal polypeptide shows sequence similarities to the Ca(2+)-ATPase and contains consensus sequence elements for phosphorylation and cell adhesion, suggesting expression of Na,K-ATPase subunits with unique functions. Using reverse transcription-polymerase chain reaction, RNA sequences for alpha 1, beta 1 and their corresponding truncated isoforms were quantified. 4.0 x 10(5) alpha 1 and 2.3 x 10(5) beta 1 molecules were found per ng of mRNA from hRPE. Much lower levels were detected for truncated alpha 1 and beta 1 (3.6 x 10(3) and 2.7 x 10(3) molecules/ng, respectively). These data corroborate the expression of truncated transcripts coding for unique aa sequences in hRPE, and suggest that factors other than alpha 1 and beta 1 mRNA levels regulate the equimolar accumulation of alpha and beta subunits in the plasma membrane.

Amino Acid Sequence↗
PubMed2004

Expression of a truncated secreted form of the mGluR3 subtype of metabotropic glutamate receptor.

In this study, 10 truncated constructs encompassing all or part of the extracellular ligand binding domain of the mGluR3 subtype of metabotropic glutamate receptor were generated, expressed in human embryonic kidney cells, and tested for secretion and binding of the high affinity agonist [(3)H]DCG-IV. The effect of inserting epitope tags into the N or C termini on cell secretion and radioligand binding was also examined. Secretion into the cell culture media was observed for 8 of the 10 truncated receptors and all secreted forms displayed high affinity agonist binding. The highest level of binding was observed in the C-terminal polyhistidine-tagged receptor truncated at serine 507. Reduction and enzymatic deglycosylation of the serine 507 truncated receptor using endoglycosidase H and PNGase F showed that the secreted receptor was a disulfide-linked dimer containing complex oligosaccharides. Pharmacological characterization demonstrated that the truncated receptor showed the same rank order of potency of agonist binding, a relatively small 2-fold decrease in agonist affinity, and a larger 10-fold decrease in affinity for the antagonist LY341495 compared to the full-length membrane-bound receptor. These results define the essential requirements for ligand binding to the extracellular domain of mGluR3 and highlight parameters important for the optimization of receptor expression in mammalian cells.

Base Sequence↗
PubMed2005

Transiently truncated and differentially regulated expression of midkine during mouse embryogenesis.

Midkine (MK) is a retinoic acid response cytokine, mostly expressed in embryonic tissues. Aberrant expression of MK was found in numerous cancers. In human, a truncated MK was expressed specifically in tumor/cancer tissues. Here we report the discovery of a novel truncated form of MK transiently expressed during normal mouse embryonic development. In addition, MK is concentrated at the interface between developing epithelium and mesenchyme as well as highly proliferating cells. Its expression, which is closely coordinated with angiogenesis and vasculogenesis, is spatiotemporally regulated with peaks in extensive organogenesis period and undifferentiated cells tailing off in maturing cells, implying its role in nascent blood vessel (endothelial) signaling of tissue differentiation and stem cell renewal/differentiation. Cloning and sequencing analysis revealed that the embryonic truncated MK, in which the conserved domain is in-frame deleted, presumably producing a novel secreted small peptide, is different from the truncated form in human cancer tissues, whose deletion results in a frame-shift mutation. Our data suggest that MK may play a role in epithelium-mesenchyme interactions, blood vessel signaling, and the decision of proliferation vs differentiation. Detection of the transiently expressed truncated MK reveals its novel function in development and sheds light on its role in carcinogenesis.

Amino Acid Sequence↗
PubMed2005

Effect of C-terminal truncation on the molecular chaperone function and dimerization of Escherichia coli trigger factor.

To examine the role of the C-terminal domain in the chaperone function of trigger factor (TF), a number of truncation mutants were constructed, namely: TF419, TF389, TF380, TF360, TF344, and TF251, in which the C-terminal 13, 43, 52, 72, 88 residues or the entire C-domain were deleted, respectively. Co-expression of mutant chicken adenylate kinase (AK) with TF and the C-terminal truncation mutants was achieved using a plasmid pBVAT that allows expression of TF and AK from a single plasmid. The results show that truncation of the C-terminus of TF has only minor effect on its ability to assist AK refolding in vivo. Further, ribosome-binding experiments indicate that C-terminal truncation mutants can still bind to the ribosome and the presence of the C-terminus may in fact lower the affinity of TF for the ribosome in vivo. This indicates that the C-domain of trigger factor may not be essential for the ribosome-associated molecular chaperone function of TF. However, the purified TF C-terminal truncation mutants had a dramatically reduced ability to assist rabbit muscle GAPDH refolding in vitro and a reduced tendency to dimerize. This shows that the structural integrity of the C-terminus contributes to both the chaperone function of TF and the stability of the dimeric form.

Adenylate Kinase↗
PubMed2006

Dominant-negative suppression of Cav2.1 currents by alpha(1)2.1 truncations requires the conserved interaction domain for beta subunits.

Episodic ataxia type 2 (EA2) is an autosomal dominant disorder arising from CACNA1A mutations, which commonly predict heterozygous expression of Ca(v)2.1 calcium channels with truncated alpha(1)2.1 pore subunits. We hypothesized that alpha(1)2.1 truncations in EA2 exert dominant-negative effects on the function of wild-type subunits. Wild-type and truncated alpha(1)2.1 subunits with fluorescent protein tags were transiently co-expressed in cells stably expressing Ca(v) auxiliary beta subunits, which facilitate alpha1 subunit functional expression through high-affinity interactions with the alpha interaction domain (AID). Co-expression of wild-type subunits with truncations often resulted in severely reduced whole-cell currents compared to expression of wild-type subunits alone. Cellular image analyses revealed that current suppression was not due to reduced wild-type expression levels. Instead, the current suppression depended on truncations terminating distal to the AID. Moreover, only AID-bearing alpha(1)2.1 proteins co-immunoprecipitated with Ca(v) beta subunits. These results indicate that Ca(v) beta subunits may play a prominent role in EA2 disease pathogenesis.

Analysis of Variance↗
PubMed2006

Truncation effects in SENSE reconstruction.

Finite sampling is an important practical issue in Fourier imaging systems. Although data truncation effects are well understood in conventional Fourier imaging where a single uniform receiver channel is used for data acquisition, this issue is not yet fully addressed in parallel imaging where an array of nonuniform receiver channels is used for sensitivity encoding to enable sub-Nyquist sampling of k-space. This article presents a systematic analysis of the problem by comparing the truncation effects in parallel imaging with those in conventional Fourier imaging. Specifically, it derives a convolution kernel function to characterize the truncation effects, which is shown to be approximately equal to that associated with the conventional Fourier imaging scheme. This article also describes a set of conditions under which significant differences between the truncation effects in parallel imaging and conventional Fourier imaging occur. The results should provide useful insight into interpreting and reducing data truncation effects in parallel imaging.

Fourier Analysis↗
PubMed2006

Presynaptic localization of a truncated isoform of the type 2 corticotropin releasing factor receptor in the cerebellum.

It is now well established that corticotropin releasing factor is present in two major excitatory afferent systems to the cerebellum, namely climbing fibers and mossy fibers. Two major classes of corticotropin releasing factor receptors, each with unique binding characteristics, have been identified as type 1 and type 2. In this study we used an antibody made to the n-terminus of the type 2 corticotropin releasing factor receptor. Characterization of this antibody showed that it strongly labeled a protein with a molecular weight of 16-32 kDa and only faintly labels a 62-83 kDa protein. The lower molecular weight protein corresponds to the weight of a recently described truncated isoform of this receptor that is designated corticotropin releasing factor-type 2alpha-truncated isoform. We carried out transfection paradigms using corticotropin releasing factor-type 2alpha-truncated isoform constructs and confirmed that the antibody recognized the truncated isoform of the type 2 corticotropin releasing factor receptor. Further, light and electron microscopic studies were carried out in mice and rats to define the distribution of the truncated receptor. Immunoreactivity is evident in the basal region of many, but not all Purkinje cell bodies and their initial axonal segments, as well as the initial axonal segments of isolated Golgi cells, and cerebellar nuclear neurons. In addition, punctate elements in the molecular layer were immunolabeled. The localization of the receptor to the initial segment of Purkinje cells was confirmed with electron microscopy. Further, the punctate labeling in the molecular layer was localized to parallel fibers and their terminals. In conclusion, evidence has been presented to show that distinct isoforms of the corticotropin releasing factor receptor are present in the cerebellum. The complex interactions between corticotropin releasing factor and other members of the corticotropin releasing factor family of peptides with both pre- and postsynaptic receptors support a growing concept that corticotropin releasing factor plays an important role in modulating activity in cerebellar circuits and ultimately in controlling motor behavior.

Adrenocorticotropic Hormone↗
PubMed2004

Rapid purification of truncated tau proteins: model approach to purification of functionally active fragments of disordered proteins, implication for neurodegenerative diseases.

Truncated tau is of great interest because of its important role in neurofibrillary pathogenesis in Alzheimer's disease (AD). A major obstacle for characterization of detailed biochemical and biological properties of truncated tau species and their fragments has been the lack of reliable and quick purification methods. Uneven distribution of acidic and basic residues in tau determines that the N- and C-terminal tau fragments require entirely different purification conditions. Conventional methods take several days; they do not allow purification of the acidic N-terminal tau fragments and do not prevent aggregation during purification that makes purified truncated tau unusable in functional studies. To prevent these inherent problems, we have designed a two-step, highly efficient purification procedure yielding a fully functional, non-aggregated homogeneous population of truncated tau molecules. Various forms of tau produced in bacteria without the need for a heat pre-treatment step were subjected to anion- and cation-exchange chromatography. Conditions were developed that allowed effective separation and purification of acidic and/or basic tau species. Following the gel filtration step, up to 10mg of tau proteins with 96% purity was obtained within one working day. Purified truncated tau exhibited an unmodified immunoreactivity and allowed its functional activity analysis. Since many neurodegenerative diseases have implicated similar disordered proteins in their pathogenesis, our procedure will allow their detailed analysis and characterization.

Blotting, Western↗
PubMed2003

Characterization of truncated mutants of human microsomal short-chain dehydrogenase/reductase RoDH-4.

Human NAD(+)-dependent microsomal short-chain dehydrogenase/reductase RoDH-4 oxidizes all-trans-retinol, 13-cis-retinol and 3alpha-hydroxysteroids to corresponding retinaldehydes and 3-ketones. RoDH-4 behaves as an integral membrane protein, but its topology in the membrane is not known. Analysis of RoDH-4 polypeptide using algorithms for secondary structure predictions suggests that RoDH-4 contains four potential membrane-spanning domains: the N-terminal, the C-terminal, and the two central hydrophobic segments. To determine the role of each segment in association of RoDH-4 with the membrane, we prepared several expression constructs coding for truncated RoDH-4 polypeptides that lacked the putative membrane-spanning domains and expressed them in insect Sf9 cells using the Baculovirus system. Association of truncated RoDH-4 constructs with the microsomal membranes was analyzed by alkaline extraction and floatation in sucrose gradient. Catalytic activity of truncated RoDH-4 constructs was assayed using the 3alpha-hydroxysteroid androsterone as substrate. Truncated RoDH-4 that lacked the first thirteen amino acids of the N-terminal segment was partially active and exhibited the apparent K(m) value for androsterone similar to that of the wild-type enzyme. Removal of 23 N-terminal hydrophobic amino acids resulted in significant loss of activity and a 14-fold increase in the apparent K(m) value. Removal of the C-terminal 27 amino acid segment resulted in a approximately 600-fold increase in the apparent K(m) value. Each truncated mutant behaved as an integral membrane protein. Furthermore, protein that lacked all four hydrophobic segments remained associated with the membrane. Thus, the N-terminal and the C-terminal ends are both important for RoDH-4 activity and the removal of the putative transmembrane segments does not convert RoDH-4 into a soluble protein, suggesting additional sites of membrane interaction.

Alcohol Oxidoreductases↗
PubMed1997

C-terminal truncation of thymosin beta10 by an intracellular protease and its influence on the interaction with G-actin studied by ultrafiltration.

Two beta-thymosins are expressed in most mammalian tissues. We detected small amounts of a third peptide in extracts of rabbit spleen. The portion of this peptide increased when the tissue was first frozen and then thawed at 4 degrees C. Small amounts of the peptide are also present in cells from suspension cultures homogenized immediately in diluted perchloric acid. By means of amino acid analysis and MALDI-mass spectroscopy this peptide was identified to be a C-terminally truncated form of thymosin beta10. Having studied the formation in more detail we found that after a 4-h thaw at 4 degrees C all thymosin beta10 was truncated to thymosin beta10(1-41), which was further degraded during the next 20 h. On the other hand, thymosin beta4Ala, the second beta-thymosin being present in rabbit spleen, was not truncated or degraded even after 22 h. It might be possible that in vivo a truncated form of thymosin beta10 is formed by a carboxydipeptidase while thymosin beta4Ala is rather stable against proteolytic modification. By using a newly designed ultrafiltration assay, we determined the dissociation constants of the complexes of G-actin and these three beta-thymosins to be 0.28, 0.72, and 0.94 microM for thymosin beta4Ala, beta10, and thymosin beta10(1-41), respectively. The complex with beta4Ala is unambiguously more stable than the complex with beta10 or beta4 (0.81 microM). The change in the dissociation constant generated by the truncation of the two C-terminal amino acid residues of beta10 is small but statistically significant. This demonstrates that even the very last amino acid residues at the C-terminus of beta-thymosins are involved in the interaction with G-actin.

Actins↗
PubMed1997

Self-association of truncated forms of HIV-1 gp120.

HIV-1 gp120 and truncated forms were expressed in HeLa T4 cells by vaccinia recombinant viruses. The truncated gp120 molecules consisted of N-terminal overlapping envelope proteins of 204, 287 and 393 amino acids respectively. Immunoprecipitation with specific monoclonal antibodies and SDS-PAGE analyses of HIV-1 gp120 revealed bands corresponding to low amounts of secreted and cell-bound stable dimers. In contrast, the truncated forms of gp120 expressed larger amounts of SDS-stable putative dimers and the amounts observed were inversely proportional to their size. The shortest gp120 mutant (204 aa) was found to be secreted almost exclusively as a dimer. The processing of gp120 and its truncated forms was further investigated in the presence of inhibitors of N-glycosylation. Monomers and dimers migrated on gels with the same relative changes, confirming that the protein with the higher molecular weight is a multimer of the smaller one. The putative dimeric form of the truncated gp120s could be stabilized by chemical cross-linking. Finally, the possible existence of an association domain in the N-terminal 204 amino acids (aa) of gp120 is discussed.

Dimerization↗