1,721,207 research outputs found
The acute phase protein α1-acid glycoprotein : a model for altered glycosylation during diseases
No full textGlycosylation is one of the most important post-translational modifications of proteins, and has been widely acknowledged as one of the most important ways to modulate both protein function and lifespan.
The acute phase proteins are a major group of serum proteins whose concentration is altered during various pathophysiological conditions.
The aim of this paper is to review the structure and functions of the α1-acid glycoprotein (AGP). AGP belongs to the subfamily of immunocalins, a group of binding proteins that also have immunomodulatory functions. One of the most interesting features of AGP is that its glycosylation microheterogeneity can be modified during diseases. This aspect is particularly remarkable, since both the immunomodulatory and the binding properties of AGP strongly depend on its carbohydrate composition. For these reasons, AGP can be considered an outstanding model for the study of glycan pattern modification during diseases. This review is focused on the most recent studies on the occurrence of different glycoforms in plasma and tissues and how the appearance of different oligosaccharide patterns during systemic inflammation or diseases can influence AGP's biological functions. The first part of the review will describe the structure of AGP and the several biological functions identified so far for this protein. The second part will be devoted to the post-translational modifications of the oligosaccharides micro-heterogeneity of AGP caused by pathological states. A critical evaluation of the impact of different AGP glycoforms on both its transport and anti-inflammatory features, and how the modifications of the glycan pattern can be utilized in clinical biochemistry, is also discussed
Infective proteins : the prion puzzle
No full textAccording to the Koch postulates an infectious organism is the one that can be isolated from an host suffering from a disorder, can be propagated in laboratory, can cause the same disease when introduced in another host, and finally, can be re-isolated from the host itself. If we change the word "organism" with the word "protein" we have a quite exact description of prions. Prion related disorders are a very unique category of infectious diseases. The ethiology of the so-called prionoses is related to the conversion of a normal protein (PrP(C), the cellular isoform of the prion protein) into a pathological form (the scrapie isoform of the prion protein, PrP(Sc)) which is able to propagate. The striking difference between the two forms seems to consist in a conformational modification of a mainly alpha-helix structured PrP(C) into a mainly beta-sheet PrP(Sc). The latter forms amyloid-like fibrils which precipitate into insoluble aggregates leading to the neurodegenerative changes specific of Spongiform Encephalopathies. This review will focus on the structure of the prion proteins and on PrP(C) cellular cycle, and it will discuss some hypothesis about the protein biochemical function. Finally, the various molecular mechanisms proposed for the development of conformational modifications will be reviewed, i.e. how a protein can become infectious by simply changing its structure
Proteomics in farm animals models of human diseases
No full textThe need to provide in vivo complex environments to understand human diseases strongly relies on the use of animal models, which traditionally include small rodents and rabbits. It is becoming increasingly evident that the few species utilised to date cannot be regarded as universal. There is a great need for new animal species that are naturally endowed with specific features relevant to human diseases. Farm animals, including pigs, cows, sheep and horses, represent a valid alternative to commonly utilised rodent models. There is an ample scope for the application of proteomic techniques in farm animals, and the establishment of several proteomic maps of plasma and tissue has clearly demonstrated that farm animals provide a disease environment that closely resembles that of human diseases. The present review offers a snapshot of how proteomic techniques have been applied to farm animals to improve their use as biomedical models. Focus will be on specific topics of biomedical research in which farm animal models have been characterised through the application of proteomic techniques
Growth at low temperature suppresses readthrough of the UGA stop codon during the expression of Bacillus subtilis flgM gene in Escherichia coli
No full textThe efficient production of recombinant proteins in Escherichia coli requires a proper termination of translation to ensure the synthesis of only the desired product. During the recombinant production of Bacillus subtilis flgM in E. coli, we detected an additional polypeptide of molecular mass higher than the expected, corresponding to a product of a translational readthrough of the UGA stop codon. In this paper we show that the readthrough was abolished when the synthesis of the recombinant protein was carried out at 25°C. The possible causes that contribute to reduce the proportion of readthrough protein species against the correct terminated product are discussed
The systemic reaction during inflammation : the acute-phase proteins
No full textThe acute-phase response consists in a large number of behavioural, physiologic, biochemical, and nutritional changes involving many organ systems distant from the site, or sites, of inflammation. One of the most investigated, but still not well understood, characteristic of the acute phase is the up-regulation, or down-regulation, of many plasma proteins, known as the acute-phase proteins. The changes in the concentrations of these positive acute-phase proteins and negative acute-phase proteins are due to changes in their liver production. Their increase may vary from 25 percent to 1000 fold, as in the case of C-reactive protein and serum amyloid A. This review summarises the recent advances that have been acquired on the acute-phase proteins, in particular their function in pathologies such as infections or inflammatory lesions
The acute phase protein α1-acid glycoprotein : a model for altered glycosylation during diseases. : Updates and new perspectives
No full text
Immunohistochemical study on the relationship between doppel protein and bovine leukocytes.
No full textDoppel (Dpl) is a prion-like protein whose sequence is notably similar to that of prion protein (PrP). Dpl is mainly expressed on testis and ovary and it is associated to neurodegeneration when ectopically expressed in transgenic mouse. PrP expression has been identified on tissue and blood leukocytes. Also Dpl has been detected on leukocytes located in germinal centers of lymphoid organs. Aim of this work is to immunohistochemically verify if also Dpl is expressed on leukocytes. This would help us to understand the biology and the mechanism of invasion of prion related protein.
Samples of spleen and lymph nodes were collected from clinically healthy bovine at slaugthering. Tissues were frozen in liquid nitrogen. Cryostatic sections were stained by immunohistochemstry using the ABC technique: bovine Dpl was identified using a polyclonal antibody; leukocyte subsets were identified with monoclonal antibodies against the following antigens: CD1 (dendritic cells); CD4 (T4 cells); CD8 (T8 cells); CD11b (monocytes and granulocytes); CD11c (myeloid cells); CD14 (macrophages) CD21 (B cells); TCR / (T cell subpopulations); MHC II (activated leukocytes).
Bovine Dpl was occasionally identified on spleen and lymph nodes. The distribution of the different leukocyte subsets in these organs, as defined by using the specific monoclonal antibodies, was normal: the Dpl-expressing leukocytes were morphologically identifiable as lyymphocytes and were localised at the periphery of germinal centers, where most of the lymphocytes were B-positive. The large part of the cells detectable on lymphoid organs, however, was Dpl negative.
Based on their morphology, localisation and immunophenotype, the Dpl positive cells in spleen and lymph nodes might be interpreted as B lymphocytes. Nevertheless, most of the cells from lymphoid organs did not express, Dpl. This suggests that the positive cells might be derived from blood. The flow cytometric identification of Dpl on blood leukocytes is required to confirm this hypothesis
cDNA cloning and Escherichia coli expression of UK114 tumor antigen
No full textExperimental evidence indicates that the antineoplastic effects of UK101, a goat liver perchloric acid extract, is likely due to one of its constituent proteins: the 14 kDa protein named UK114. The cDNA encoding UK114, obtained by PCR methodologies, contains an open reading frame coding for a protein of 137 amino acids with a theoretical molecular mass of 14298 Da. It shows high sequence homology with a 14 kDa protein identified in human, rat and Mus musculus tissues which is likely involved in the inhibition of cell-free protein synthesis. Northern blot analysis indicated that the transcript is present in variable amounts in a wide range of human tissues. Genomic Southern blots revealed that the UK114 mRNA in goat as well as in human is encoded by a single gene, as is the case in rat. The expression system for UK114 was constructed under the control of the PL promoter from bacteriophage lambda and the cDNA coding region has been highly expressed in Escherichia coli as a thioredoxin fusion protein. The recombinant UK114, purified to homogeneity, is immunoreactive to rabbit antisera prepared against UK101 or native UK114, as well as to sera of UK101-treated cancer patients. It inhibits cell-free protein synthesis at 8 microM concentration
- …
