scholarly journals Molecular interaction of the proteasome (multicatalytic proteinase). Evidence that the proteasome is not a constituent of the ‘26 S’ multienzyme complex

1991 ◽  
Vol 280 (1) ◽  
pp. 225-232 ◽  
Author(s):  
A Seelig ◽  
P M Kloetzel ◽  
L Kuehn ◽  
B Dahlmann
Keyword(s):  
Molecular Mass ◽  
Molecular Interaction ◽  
Gradient Centrifugation ◽  
Mass Range ◽  
High Molecular Mass ◽  
Multienzyme Complex ◽  
Multicatalytic Proteinase ◽  
Sds Page ◽  
Specific Antisera ◽  
Rabbit Reticulocytes

On the basis of recent reports that suggested that proteasomes, via an ATP-dependent process, become integral components of a ‘26 S’ complex possessing 3-carboxypropionyl-Leu-Leu-Val-Tyr 4-methylcoumarin-7-ylamide-hydrolysing activity, we have investigated the molecular interaction of proteasomes in ATP-stabilized fraction II (proteins absorbed on DEAE-matrix and eluted with 0.5 M-KCl) of rabbit reticulocytes and mouse liver. Analysis of the various extracts by (NH4)2SO4 fractionation, velocity-gradient centrifugation, non-denaturing PAGE and SDS/PAGE and immunoblotting with proteasome-specific antisera failed to identify the proteasome as part of a higher-molecular-mass ‘26 S’ multienzyme complex. In all instances proteasomes are identified in their ‘free’ 650 kDa ‘20 S’ form. In addition to the proteasome and independent of the presence of MgATP, we isolated a high-molecular-mass proteinase whose electrophoretic migration behaviour and sedimentation rate correspond to that of the previously described ‘26 S’ proteinase. This ‘26 S’ proteinase possesses a strong 3-carboxypropionyl-Leu-Leu-Val-Tyr 4-methylcoumarin-7-ylamide-hydrolysing activity and is composed of several non-identical polypeptides in the molecular-mass range 20-150 kDa. Despite its similarity to proteasomal enzyme activity, protein analysis and immunoblotting experiments demonstrate that neither the intact proteasome nor subunits thereof are components of the ‘26 S’ proteinase complex.

scholarly journals PROTEINS OF PAROTOID GLAND SECRETIONS FROM TOADS OF THE GENUS BUFO

2000 ◽  
pp. 1-7 ◽  
Author(s):  
David Perry
Keyword(s):  
Amino Acid ◽  
Molecular Mass ◽  
Mass Range ◽  
Relative Molecular Mass ◽  
Terminal Amino Acid ◽  
Banding Patterns ◽  
Freeze Dried ◽  
Sds Page ◽  
Terminal Amino ◽  
Terminal Amino Acid Sequence

Freeze-dried parotoid gland secretions from toads of the genus Bufo contained large proportions of protein (25-35% by weight). SDS-PAGE suggested that secretions from several species of Bufo contained mixtures of proteins in the relative molecular mass range of approximately 12 - 200 kDa, which exhibited markedly different banding patterns from species to species. These proteins were presumably not discovered before because the previous extraction procedures used with these secretions were designed to examine low molecular mass compounds and would denature the proteins. SDS-PAGE of secretions from B. mauritanicus and B. calamita are shown here. The N-terminal amino acid sequence of one of the bands (approx. 58 kDa) of B. mauritanicus was found to be LPIPAFPGLDHGF and of a B. calamita band (30.5 kDa) was VQVFGLQKEA. No significant similarities to these two sequences and to three separate but partial N-terminal sequences obtained from these species were found in genetic databases.

scholarly journals Identification of a human gastric mucin precursor: N-linked glycosylation and oligomerization

1994 ◽  
Vol 304 (3) ◽  
pp. 693-698 ◽  
Author(s):  
L W J Klomp ◽  
L van Rens ◽  
G J Strous
Keyword(s):  
Molecular Mass ◽  
Mechanical Damage ◽  
Polyclonal Antiserum ◽  
High Molecular Mass ◽  
Apparent Molecular Mass ◽  
Gastric Mucin ◽  
Gastric Mucus ◽  
Apical Side ◽  
Sds Page ◽  
Glycosylation Inhibitor

Gastric mucin plays an important role in the protection of the stomach wall from chemical, microbiological and mechanical damage. We have previously isolated human gastric mucus glycoproteins and raised a polyclonal antiserum against these macromolecules. This antiserum specifically reacted with gastric mucins in immunoblotting experiments and stained mucous granules at the apical side of gastric surface epithelial cells. A similar staining pattern was obtained after incubation with an antiserum against rat gastric mucin. Next we used the antiserum in pulse-chase experiments of human stomach tissue explants. After short labelling periods with [35S]methionine and [35S]cysteine, the antiserum reacted with a polypeptide with an apparent molecular mass of approx. 500 kDa as determined by SDS/PAGE, which was converted after 90 min into a heterogeneous high-molecular-mass glycoprotein. This high-molecular-mass form, but not the 500 kDa polypeptide, was detectable in the culture medium after 2 h. This strongly suggests that the 500 kDa polypeptide is the precursor of the purified gastric mucin. Analysis of pulse-chase experiments by non-reducing SDS/PAGE revealed that the precursors form disulphide-linked oligomers early in biosynthesis, before the addition of O-linked sugars. After preincubation with the N-glycosylation inhibitor, tunicamycin, the apparent molecular mass of the precursor decreased marginally but consistently, indicating that N-linked glycan chains are present on the mucin precursor.

scholarly journals Mucins secreted by a transformed cell line derived from human tracheal gland cells1

1997 ◽  
Vol 326 (2) ◽  
pp. 431-437 ◽  
Author(s):  
Jean-Marc LO-GUIDICE ◽  
Marc D. MERTEN ◽  
Geneviève LAMBLIN ◽  
Nicole PORCHET ◽  
Marie-Christine HOUVENAGHEL ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Cell Line ◽  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Buoyant Density ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
High Molecular Mass ◽  
Cscl Density Gradient

High-molecular-mass glycoconjugates are secreted by the continuous cell line MM-39, which has been obtained from cultured human tracheal gland cells transformed by simian virus 40. They were purified on Sepharose® CL-4B and then by two steps of density-gradient centrifugation. High-molecular-mass glycoproteins resistant to digestion by hyaluronidase, chondroitin ABC lyase and heparitinase were obtained, in addition to hyaluronic acid and proteoglycans. They were susceptible to β-elimination. They contained polylactosaminoglycan chains as well as carbohydrate chains with a terminal sialic acid in the NeuAc α2-3 sequence. Most of them have a buoyant density of 1.45 g/ml in CsCl-density-gradient centrifugation, except for MUC1. The MM-39 cells were also characterized by a high expression of MUC1 and MUC4 genes, but they did not express MUC2, MUC3, MUC5B and MUC5AC. Therefore the MM-39 cells synthesized mucin-like glycoproteins as well as lysozyme and mucous proteinase inhibitor [Merten, Kammouni, Renaud, Birg, Mattéi and Figarella (1996) Am. J. Respir. Cell. Mol. Biol. 15, 520–528]; they should be considered as having a mixed, both serous and mucous, phenotype.

scholarly journals Biosynthesis of rat MUC2 in colon and its analogy with human MUC2

1995 ◽  
Vol 309 (1) ◽  
pp. 221-229 ◽  
Author(s):  
K M A J Tytgat ◽  
F J Bovelander ◽  
F J M Opdam ◽  
A W C Einerhand ◽  
H A Büller ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Buoyant Density ◽  
Polyclonal Antiserum ◽  
High Molecular Mass ◽  
Rat Colon ◽  
Metabolic Labelling ◽  
Colonic Mucin ◽  
Sds Page ◽  
High Degree ◽  
Degree Of Similarity

In order to identify the mucins synthesized and secreted in the rat colon, we studied their biochemical characteristics and biosynthesis and evaluated their analogy to human colonic mucins. Purified mucin from both species appeared similar with respect to composition, buoyant density and mobility on SDS/PAGE. Isolated rat colonic mucin (RCM) was used to elicit a polyclonal antiserum, which was used in metabolic labelling studies to identify mucins and mucin precursors. RCM is synthesized as a 600 kDa precursor protein, which oligomerizes before O-glycosylation. The mature, high-molecular mass mucin is secreted and displays an anomalous molecular mass on SDS/PAGE of approximately 650 kDa. Polymorphism in precursor size was found among different rats, suggesting genetic heterogeneity. Molecular mass, biosynthesis and secretion of RCM appeared similar to human MUC2. Moreover, RCM precursor could be immunoprecipitated using specific anti-(human MUC2) antisera, indicating that the RCM can be designated rat MUC2. This study describes the biosynthesis of two homologous mucins in two different species. The high degree of similarity suggests functional analogy.

scholarly journals Purification and partial characterization of the major cell-associated heparan sulphate proteoglycan of rat liver

1991 ◽  
Vol 273 (2) ◽  
pp. 415-422 ◽  
Author(s):  
M Lyon ◽  
J T Gallagher
Keyword(s):  
Molecular Mass ◽  
Proteinase Inhibitors ◽  
Gradient Centrifugation ◽  
Heparan Sulphate ◽  
Exchange Chromatography ◽  
Guanidinium Chloride ◽  
Apparent Homogeneity ◽  
Core Proteins ◽  
Sds Page ◽  
Triton X

Heparan sulphate proteoglycans were solubilized from whole rat livers by homogenization and dissociative extraction with 4 M-guanidinium chloride containing Triton X-100 and proteinase inhibitors. The extract was subjected to trichloroacetic acid precipitation and the proteoglycan remained soluble. This was then purified to apparent homogeneity by a combination of (a) DEAE-Sephacel chromatography, (b) digestion with chondroitinase ABC followed by f.p.l.c. Mono Q ion-exchange chromatography, and (c) density-gradient centrifugation in CsCl and 4 M-guanidinium chloride. Approx. 1.5 mg of proteoglycan was obtained from 30 livers with an estimated recovery of 25%. The purified proteoglycan was eluted from Sepharose CL6B as an apparently single polydisperse population with a Kav. of 0.19 and displayed a molecular mass of greater than or equal to 200 kDa (relative to protein standards) by SDS/PAGE. Its heparan sulphate chains were eluted with a Kav. of 0.44 and have an estimated molecular mass of 25 kDa. Digestion of the proteoglycan with a combination of heparinases yielded core proteins of 77, 49 and 44 kDa. Deglycosylation using trifluoromethanesulphonic acid, though slightly decreasing the sizes, gave an identical pattern of core proteins. Electrophoretic detergent blotting demonstrated that all of the core proteins were hydrophobic and are probably integral plasma membrane molecules. The peptide maps generated by V8 proteinase digestion of the two major core proteins (77 and 49 kDa) were very similar, suggesting that these two core proteins are structurally related.

A dolichol acyltransferase present in rat and human postheparin plasma

1992 ◽  
Vol 70 (6) ◽  
pp. 470-474 ◽  
Author(s):  
P. Sindelar ◽  
C. Valtersson
Keyword(s):  
Cell Surface ◽  
Molecular Mass ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
High Molecular Mass ◽  
Gel Chromatography ◽  
Heat Treated ◽  
A Cell ◽  
Small Unilamellar Vesicles ◽  
Plasma Heparin

Incubation of small unilamellar vesicles consisting of dioleoyl phosphatidylcholine – dioleoyl phosphatidylethanolamine (3:1) and 2 mol% [3H]dolichol-19 with postheparin plasma from rat resulted in the formation of dolichyl oleate. Normal plasma or heat-treated postheparin plasma contained no activity and, hence, the results indicate the presence of a cell surface associated dolichol acyltransferase that can be released into the blood by heparin. The reaction is strongly stimulated by phosphatidylethanolamine and Ca2+, whereas no stimulation with triglycerides or acyl-CoA was observed. Together with the fact that the only product formed was dolichyl oleate, these results strongly suggest that a transacylation mechanism from the phospholipids to dolichol is operative in the liposomes. Gel chromatography of postheparin plasma yielded a molecular mass of about 350 kilodaltons for the active enzyme and density gradient centrifugation indicated that this high molecular mass complex consists mainly of proteins. Finally, we conclude that this enzyme is not unique to the rat, but is also present in human postheparin plasma.Key words: phospholipids, dolichol, plasma, heparin, acyltransferase(s).

scholarly journals Human leucocyte glycosylasparaginase is an α/β-heterodimer of 19 kDa α-subunit and 17 and 18 kDa β-subunit

1994 ◽  
Vol 300 (2) ◽  
pp. 541-544 ◽  
Author(s):  
O K Tollersrud ◽  
T Heiskanen ◽  
L Peltonen
Keyword(s):  
Molecular Mass ◽  
Reversed Phase ◽  
Alpha Subunit ◽  
Cross Linking ◽  
Terminal Sequence ◽  
Α Subunit ◽  
Sds Page ◽  
Specific Antisera ◽  
Purification Scheme ◽  
Chemical Cross Linking

Human lysosomal glycosylasparaginase (AGA; EC 3.5.1.26) consists of two glycosylated subunits, alpha and beta. Treatment with 3% SDS at 45 degrees C as part of a new purification scheme did not affect enzyme activity, but the alpha-subunit migrated an apparent 19 kDa peptide on SDS/PAGE instead of as a 24 kDa peptide, as observed without this SDS treatment. The N-terminal sequence was similar to that of the 24 kDa form, and, after reversed-phase h.p.l.c., the 19 kDa form was transformed to an apparent 24 kDa peptide on SDS/PAGE, indicating that their primary structures were identical. As the molecular mass of the alpha-subunit deduced from its cDNA was 19.5 kDa, the variation might be due to incomplete SDS coating of the 24 kDa form. This was confirmed by the tendency of the 24 kDa variant to polymerize even in the presence of SDS. The molecular mass of the beta-subunit was 17 and 18 kDa in accordance with previous reports. Chemical cross-linking with 1-ethyl-3-(3-dimethylaminopropyl)carbodi-imide resulted in the appearance of a 38 kDa peptide on SDS/PAGE which reacted with both the subunit-specific antisera on Western-blot analysis. On SDS/PAGE at pH 10.2 the active enzyme migrated as an apparent 43 kDa peptide. These results indicate that native human glycosylasparaginase is a heterodimer.

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