scholarly journals Secretion, cleavage and binding of complement component C3 by the human monocytic cell line U937

1989 ◽  
Vol 261 (2) ◽  
pp. 407-413 ◽  
Author(s):  
C M Maison ◽  
C L Villiers ◽  
M G Colomb
Keyword(s):  
Gel Electrophoresis ◽  
Alternative Pathway ◽  
Polyacrylamide Gel Electrophoresis ◽  
Complement Component ◽  
Polyacrylamide Gel ◽  
Classical Pathway ◽  
U937 Cells ◽  
Complement Component C3 ◽  
Thioester Bond ◽  
Membrane Bound

Secretion of complement component C3 by U937 cells was studied. Preliminary evidence for a cell-associated proteolytic activity specific for C3 is given, as well as for a covalent-like binding of C3 fragments to the cell membranes. Secretion of C3, in the presence of 10 ng of phorbol 12-myristate 13-acetate/ml, is 120-140 ng/10(6) cells per 24 h on the third day after addition of the activator. As shown by SDS/polyacrylamide-gel electrophoresis, the intracellular pro-C3 (200 kDa) and the extracellular secreted C3 (alpha-chain 110 kDa and beta-chain 75 kDa) are identical with the forms of C3 previously characterized from human serum. Incubation of U937 cells in the presence of exogenous radiolabelled C3 shows that membrane-bound proteinase(s), not related to the classical-pathway or the alternative-pathway C3 convertases, is (are) able to cleave C3; this cleavage leads to the binding of the resulting C3 fragments to the cell membrane through reaction of membrane acceptors with the carbonyl group of C3 revealed after disruption of the intramolecular thioester bond. The proteolysis appears to be fairly specific to C3, as C4, which also possesses an intramolecular thioester bond, is not cleaved and does not bind to the cells. p-Nitrophenyl p'-guanidinobenzoate (1 mM) and di-isopropyl phosphorofluoridate (2 mM) are potent inhibitors of the proteolysis, whereas soya-bean trypsin inhibitor (1 mM), leupeptin (0.1 mg/ml) and 1,10-phenanthroline (1 mM) were ineffective. Immunological characterization of the cell-bound C3 fragments with monoclonal antibodies shows an evolution of the proteolysis of the fragments from iC3b to C3dg epitopes. Extraction of membrane-bound fragments by detergent, followed by SDS/polyacrylamide-gel electrophoresis, shows two fragments, of 43 kDa and 46 kDa, with C3dg-like characteristics.

scholarly journals Membrane proteins of chromaffin granules. Dopamine β-hydroxylase, a major constituent

1972 ◽  
Vol 129 (1) ◽  
pp. 187-195 ◽  
Author(s):  
Heide Hörtnagl ◽  
H. Winkler ◽  
H. Lochs
Keyword(s):  
Membrane Proteins ◽  
Gel Electrophoresis ◽  
Cetylpyridinium Chloride ◽  
Polyacrylamide Gel Electrophoresis ◽  
Polyacrylamide Gel ◽  
Major Constituent ◽  
Chromaffin Granules ◽  
Lower Mobility ◽  
Membrane Bound ◽  
Immunological Cross Reaction

1. Soluble lysates and membranes were prepared from chromaffin granules isolated from bovine adrenal medulla. The detergent N-cetylpyridinium chloride was used for solubilizing the membrane proteins, including the membrane-bound dopamine (2,4-dihydroxyphenethylamine) β-hydroxylase. The solubilized proteins were fractionated by Sephadex chromatography in the presence of N-cetylpyridinium chloride. The major component of the membrane proteins, i.e. chromomembrin A, was identified as the enzyme dopamine β-hydroxylase. 2. The addition of N-cetylpyridinium chloride to the soluble lysate caused precipitation of up to 96% of the proteins, but only a small proportion of the dopamine β-hydroxylase activity was precipitated. The only protein demonstrable in the supernatant by polyacrylamide-gel electrophoresis was the protein that has a lower mobility than chromogranin A in disc gel electrophoresis. This component has been identified previously as dopamine β-hydroxylase. Thus, this method provides an extremely simple isolation procedure for dopamine β-hydroxylase. 3. A comparison of the membrane-bound and soluble dopamine β-hydroxylases revealed the identity of these two preparations. Both were activated by N-cetylpyridinium chloride, they migrated identically in polyacrylamide-gel electrophoresis, their amino acid composition was very similar and an immunological cross-reaction could be demonstrated.

Synthesis of Albumin with Exogenous Mouse-Liver Messenger RNA in a Homologous Cell-Free System

1974 ◽  
Vol 52 (5) ◽  
pp. 429-432 ◽  
Author(s):  
A. J. Faber ◽  
S. H. Miall ◽  
T. Tamaoki
Keyword(s):  
Protein Synthesis ◽  
Total Protein ◽  
Gel Electrophoresis ◽  
Messenger Rna ◽  
Mouse Liver ◽  
Polyacrylamide Gel Electrophoresis ◽  
Polyacrylamide Gel ◽  
Free System ◽  
Cell Free System ◽  
Membrane Bound

RNA extracted from total and membrane-bound polysomes of mouse liver was capable of directing protein synthesis in a homologous cell-free system in the presence of a 0.5 M KCl ribosomal wash fraction. Analysis of the products by polyacrylamide gel electrophoresis and immunoprecipitation showed that newly formed albumin could account for up to 8% of the total protein synthesized.

Ultrastructural localization of specific nucleoprotein fractions

1978 ◽  
Vol 36 (2) ◽  
pp. 204-205
Author(s):  
G. L. Brown
Keyword(s):  
Gel Electrophoresis ◽  
Mouse Liver ◽  
Polyacrylamide Gel Electrophoresis ◽  
Ultrastructural Localization ◽  
Polyacrylamide Gel ◽  
Acid Extraction ◽  
Acid Solutions ◽  
Low Salt ◽  
Liver Nuclei ◽  
Phosphate Groups

Bismuth (Bi) stains nucleoproteins (NPs) by interacting with available amino and primary phosphate groups. These two staining mechanisms are distinguishable by glutaraldehyde crosslinking (Fig. 1,2).Isolated mouse liver nuclei, extracted with salt and acid solutions, fixed in either formaldehyde (form.) or gl utaraldehyde (glut.) and stained with Bi, were viewed to determine the effect of the extractions on Bi stainina. Solubilized NPs were analyzed by SDS-polyacrylamide gel electrophoresis.Extraction with 0.14 M salt does not change the Bi staining characteristics (Fig. 3). 0.34 M salt reduces nucleolar (Nu) staining but has no effect on interchromatinic (IC) staining (Fig. 4). Proteins responsible for Nu and glut.- insensitive IC staining are removed when nuclei are extracted with 0.6 M salt (Fig. 5, 6). Low salt and acid extraction prevents Bi-Nu staining but has no effect on IC staining (Fig. 7). When nuclei are extracted with 0.6 M salt followed by low salt and acid, all Bi-staining components are removed (Fig. 8).

Platelet Microtubule Subunit Proteins

1979 ◽  
Vol 42 (05) ◽  
pp. 1630-1633 ◽  
Author(s):  
A G Castle ◽  
N Crawford
Keyword(s):  
Epithelial Cells ◽  
Gel Electrophoresis ◽  
Blood Platelets ◽  
Polyacrylamide Gel Electrophoresis ◽  
Polyacrylamide Gel ◽  
Lens Epithelial Cells ◽  
Molecular Weights ◽  
Kinetics Of ◽  
Microtubular Structures

SummaryBlood platelets contain microtubule proteins (tubulin and HMWs) which can be polymerised “in vitro” to form structures which resemble the microtubules seen in the intact platelet. Platelet tubulin is composed of two non-identical subunits a and p tubulin which have molecular weights around 55,000 but can be resolved in alkaline SDS-polyacrylamide gel electrophoresis. These subunits associate as dimers with sedimentation coefficients of about 5.7 S although it is not known whether the dimer protein is a homo- or hetero-dimer. The dimer tubulin binds the anti-mitotic drug colchicine and the kinetics of this binding are similar to those reported for neurotubulins. Platelet microtubules also contain two HMW proteins which appear to be essential and integral components of the fully assembled microtubule. These proteins have molecular weights greater than 200,000 daltons. Fluorescent labelled antibodies to platelet and brain tubulins stain long filamentous microtubular structures in bovine lens epithelial cells and this pattern of staining is prevented by exposing the cells to conditions known to cause depolymerisation of cell microtubules.

Prothrombin Metz : Purification and Characterization of a Variant of Human Prothrombin

1979 ◽  
Author(s):  
M Ribieto ◽  
J Elion ◽  
D Labie ◽  
F Josso
Keyword(s):  
Molecular Weight ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Factor Xa ◽  
Polyacrylamide Gel ◽  
Cleavage Pattern ◽  
Purification And Characterization ◽  
Double Immunodiffusion ◽  
The Family

For the purification of the abnormal prothrombin (Pt Metz), advantage has been taken of the existence in the family of three siblings who, being double heterozygotes for Pt Metz and a hypoprothrombinemia, have no normal Pt. Purification procedures included barium citrate adsorption and chromatography on DEAE Sephadex as for normal Pt. As opposed to some other variants (Pt Barcelona and Madrid), Pt Metz elutes as a single symetrical peak. By SDS polyacrylamide gel electrophoresis, this material is homogeneous and appears to have the same molecular weight as normal Pt. Comigration of normal and abnormal Pt in the absence of SDS, shows a double band suggesting an abnormal charge for the variant. Pt Metz exhibits an identity reaction with the control by double immunodiffusion. Upon activation by factor Xa, Pt Metz can generate amydolytic activity on Bz-Phe-Val-Arg-pNa (S2160), but only a very low clotting activity. Clear abnormalities are observed in the cleavage pattern of Pt Metz when monitored by SDS gel electrophoresis. The main feature are the accumulation of prethrombin l (Pl) and the appearance of abnormal intermediates migrating faster than Pl.

Functional Relationship of Polymerization Sites of Vertebrate Fibrinogens

1979 ◽  
Author(s):  
C Cierniewski ◽  
T Krajewski ◽  
E Janiak
Keyword(s):  
Gel Electrophoresis ◽  
Functional Relationship ◽  
Polyacrylamide Gel Electrophoresis ◽  
Polyacrylamide Gel ◽  
Functional Similarity ◽  
Fractionation Method ◽  
Relationship Of ◽  
Fibrin Monomers ◽  
Fibrinogen Molecule ◽  
Cold Ethanol Fractionation

Various studies on the interaction of immobilized mammalian fibrinogen and fibrin monomers with some fibrinogen derivatives demonstrated the presence of two sets of polymerization sites in the mammalian fibrinogen molecule. We obtained the same results while investigating the fibrinogen molecules of other classes of vertebrates /Pisces. Amphibia. Aves/. Despite significant differences among their subunit structures, all of them contain polymerization sites homologous to mammalian counterparts. Moreover, due to great functional similarity, fibrinogen or fibrin monomers of the analyzed species of Pisces. Amphibia. Aves and Mammalia interacted in a specific way with immobilized pig fibrin monomers or fibrinogen, respectively. Using these pig affinity adsorbents, fibrinogen and fibrin monomers of different vertebrates were isolated directly from plasma and analyzed by SDS polyacrylamide gel electrophoresis. Polypeptide compositions of eluted proteins were identical to those obtained for corresponding fibrinogen preparations isolated by cold-ethanol fractionation method. It appears to indicate that the nature of polymerization sites in vertebrate fibrinogens is alike.

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