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1.
The initial time and rate of myelin basic protein synthesis in neural tissues of the rat have been measured from birth to 120 days. The protein was quantitated by a radioimmunoassay directly applied to unfractionated cerebrum, cerebellum, olfactory bulb, midbrain, brain stem, optic and trigeminal nerve, and areas of the spinal cord. Because the protein is a specific myelin constituent and its appearance correlates precisely with the synthesis of myelin lipids, the data in this report can be interpreted in terms of myelin synthesis and oligodendrocyte activity. The results show striking heterogeneity in the initial time and rate of myelin synthesis in neural tissue. 相似文献
2.
1. Myeline proteins in bovine peripheral nerve migrated as two main band-(BF and BR protein) and one faint middle band (BM protein) on sodium dodecyls sulfate-polyacrylamide gel electrophoresis. The relative mobility of these two main bands differed from those of myelin proteins in the central nervous system. 2. The acid extract of the myelin fraction from bovine peripheral nerve was separated into one main peak and two minor peaks on a Sephadex G-75 column. The major component of the second minor peak was the BM protein; the major component of the main peak was the BF protein. The BR protein was not extractable by acid solution. 3. Molecular weights of the BF, the BM and the BR protein were determined as around 13 000, 20 000 and 28 000, respectively, by sodium dodecylsulfate-polyacrylamide gel electrophoresis. 4. The amino acid composition of the BF protein was quite different from the encephalitogenic protein and the Folch-Lees type proteolipid protein in the central nervous system. However the BM protein showed similar amino acid composition to the encephalitogenic protein. 5. The tryptic peptide maps of the BF protein and of the encephalitogenic protein were quite different. The results suggested that the amino acid sequences of these two proteins are different and that they contain no common tryptophan-containing peptide. 相似文献
3.
C W Campagnoni G D Carey A T Campagnoni 《Archives of biochemistry and biophysics》1978,190(1):118-125
Mice ranging in age from 14 to 39 days were injected intracerebrally with [3H]lysine and rates of incorporation of the isotope were measured into total trichloroacetic acid-precipitable protein and purified myelin basic proteins (MBPs). MBPs were isolated by O-(carboxymethyl)-cellulose chromatography of pH 3 extracts prepared from chloroform-methanol insoluble residues of whole brains. The MBPs prepared in this fashion were further separated by polyacrylamide gel electrophoresis. The gels were sliced and the radioactivity incorporated into each of the two proteins was determined. Analysis of the rates of synthesis of the two basic proteins (using a 2-h labeling period) as a function of age revealed that synthesis of both proteins appeared to peak at about 18 days of age in the mouse. These data suggest that the maximum rate of MBP synthesis coincides with the age of maximal myelin deposition in the mouse. Furthermore the relative rates of synthesis of L and S changed considerably over the developmental period examined. It was observed that the ratio of the rates of synthesis of the small:large basic protein (S/L) increased by approximately 50% between 2 and 4 weeks and declined thereafter. Throughout the developmental period examined, however, the small basic protein appeared to be synthesized at a greater rate than the large protein. The latter data are consistent with previous observations by us and other workers that mouse and rat myelin becomes increasingly enriched in the small relative to the large basic protein with maturation of the membrane. 相似文献
4.
The relative proportions of four myelin basic proteins (preL, L, preS,S) were determined in myelin subfractions prepared from the forebrains of quaking and littermate control mice. The distribution pattern of each protein was similar in both mutant and control fractions. The S component was the only basic protein present in low amounts in myelin from the mutant. 相似文献
5.
We have investigated the effect of chloroform on the phosphorylation of myelin basic proteins because tumor-promoting agents such as phorbol esters and chloroform are known to enhance the activity of protein kinase C. We report that the presence of chloroform, at a concentration known to enhance protein kinase C activity, stimulated the phosphorylation of myelin basic proteins 15-17 fold over control conditions. The phosphorylation of a 50 kiloDalton myelin protein was also stimulated but to a lesser extent. The concentration of chloroform required for the maximal phosphorylation of myelin basic proteins and the 50 kiloDalton protein was approximately 2% (v/v). 相似文献
6.
Myelin was isolated from the brains of mice 15, 20, 30, and 60 days after birth. The total amount of basic protein present in the isolated myelin was determined by radioimmunoassay. The 4 myelin basic proteins, with molecular weights of 21,500, 18,500, 17,000 and 14,000, were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and their relative amounts were determined densitometrically. The absolute amount of each of the basic proteins was calculated from its relative amount on the gel and from the total amount of myelin basic protein in the sample as determined by radioimmunoassay. The results show that between 10 and 30 days after birth each protein accumulates at a characteristic rate so that the molar ratios among the 4 basic proteins are (in descending order according to their molecular weights) 1:5:2:10 during this period. Between 30 and 60 days after birth the 14 K and 18.5 K proteins continue to accumulate at reduced rates while the 21.5 K and 17 K proteins begin to disappear from the myelin membrane; 60 days after birth the molar ratios among the 4 basic proteins are 1:10:3.5:35. These developmental patterns of accumulation are discussed in relation to the possible role of each of the 4 myelin basic proteins in myelination. 相似文献
7.
Susan M. Staugaitis David R. Colman Liliana Pedraza 《BioEssays : news and reviews in molecular, cellular and developmental biology》1996,18(1):13-18
The myelin basic proteins are a set of peripheral membrane polypeptides which play an essential role in myelination. Their most well-documented property is the unique ability to ‘seal’ the cytoplasmic aspects of the myelin membrane, but this is probably not the only function for these highly charged molecules. Despite extensive homology, the individual myelin basic proteins (MBPs) exhibit different expression patterns and biochemical properties, and so it is now believed that the various isoforms are not functionally equivalent in myelinating cells. We now think that while the major MBPs are intracellular adhesion molecules, some of the quantitatively less abundant isoforms that are expressed very early in development may have regulatory effects on the myelination program. 相似文献
8.
Myelin from developing rat brain (8–44 day-old rat) was incubated in vitro with [-32P]ATP to determine how many basic proteins were phosphorylated. Myelin proteins were separated by polyacrylamide gel electrophoresis and transferred to nitrocellulose sheets. The nitrocellulose sheets were stained with antisera to human basic protein by the immunoblot technique. Five basic proteins with molecular weights of 23K, 21.5K, 18.5K, 17K, and 14K were distinctly immunostained. These basic proteins were found to be phosphorylated when the same nitrocellulose sheets were exposed to x-ray film. The in vitro phosphorylation of 23K and 21.5K basic proteins appear to decrease with maturation of the brain. The result of this study suggests that intense phosphorylation of various forms of basic proteins, in particular 23K and 21.5K basic proteins, during the initial stages of myelin formation, may play a pivotal role in the compaction of myelin membrane. 相似文献
9.
Ox peripheral nerve myelin membrane. Purification and partial characterization of two basic proteins 总被引:6,自引:0,他引:6
Y London 《Biochimica et biophysica acta》1971,249(1):188-196
10.
Chromatographic studies were performed to measure myelin basic protein (MBP) interactions by covalently binding a number of different proteins to Sepharose and passing radioactive bovine MBP over these columns. Studies at a variety of pH values, ionic strengths and temperatures revealed that the bovine MBP could interact with itself as well as cytochrome c, lysozyme, and ovalbumin. Chromatographic profiles of elution volume vs. pH revealed that the interaction between MBP and these immobilized proteins was biphasic. The self-association of MBP was found to be strongest between pH 7.4 and 8.1 and at an elevated temperature. Titration of the amino acid residues responsible for the association of MBP with other proteins revealed apparent pKs ranging from 6.10 to 6.70. A pH dependence study at an elevated temperature shifted the apparent pK of the MBP interaction to a lower value with all the proteins except ovalbumin. After destroying 60% of the histidine residues in MBP by photooxidation and passing125I-labeled photooxidized MBP over Sepharose columns containing immobilized protein, the second phase in binding was decreased significantly with immobilized cytochrome c, lysozyme, and MBP and to a smaller extent with ovalbumin. These results are consistent with the involvement of deprotonated histidine residues in the MBP-protein associations. 相似文献
11.
Harish C. Agrawal Keith O''Connell Charlotte L. Randle Daya Agrawal 《The Biochemical journal》1982,201(1):39-47
When rat brain myelin was examined by sodium dodecyl sulphate/polyacrylamideslab-gel electrophoresis followed by fluorography of the stained gel, it was found that a host of proteins of rat brain myelin were labelled 2, 4 and 24h after the intracerebral injection of H332PO4. Among those labelled were proteins migrating to the positions of myelin-associated glycoprotein, Wolfgram proteins, proteolipid protein, DM-20 and basic proteins. The four basic proteins with mol.wts. 21000, 18000 (large basic protein), 17000 and 14000 (small basic protein) were shown to be phosphorylated after electrophoresis in both acid-urea- and sodium dodecyl sulphate-containing gel systems followed by fluorography. The four basic proteins imparted bluish-green colour, after staining with Amido Black, which is characteristic of myelin basic proteins. The four basic proteins were purified to homogeneity. Fluorography of the purified basic proteins after re-electrophoresis revealed the presence of phosphorylated high-molecular-weight `polymers' associated with each basic protein. The amino acid compositions of the phosphorylated large basic protein and small basic proteins are compatible with the amino acid sequences. Proteins with mol.wts. 21000 and 17000 gave the expected amino acid composition of myelin basic proteins. Radiolabelled phosphoserine and phosphothreonine were identified after partial acid hydrolysis of the four purified basic proteins. The [32P]phosphate–protein bond in the basic protein was stable at an acidic pH but was readily hydrolysed at alkaline pH, as would be expected of phosphoester bonds involving both serine and threonine residues. Double-immunodiffusion analysis demonstrated that the four phosphorylated proteins showed complete homology when diffused against antiserum to a mixture of small and large basic proteins. Since the four basic proteins of rat brain myelin were phosphorylated both in vivo and in vitro it is postulated that the same protein kinase is responsible for their phosphorylation in both conditions. 相似文献
12.
13.
L S Smith C W Kern R M Halpern R A Smith 《Biochemical and biophysical research communications》1976,71(2):459-465
Isolated rat brain myelin when incubated with γ32P labelled ATP yields proteins bearing acid labile, base stable phosphoryl groups. Phosphorylated myelin basic protein can be isolated and degraded with trypsin and pronase to yield principally phosphoarginine and phosphohistidine. Only a very small amount of phosphorerine survives the base treatment used in the isolation procedure. 相似文献
14.
Interaction of calmodulin with chromatin associated proteins and myelin basic protein 总被引:1,自引:0,他引:1
Chromatin associated proteins such as histone and protamine and myelin basic protein inhibit the activities of calmodulin-dependent cyclic nucleotide phosphodiesterase and myosin light chain kinase supported by Ca2+ and calmodulin in a dose-dependent manner. The inhibition of these enzymes induced by the proteins is completely abolished by high concentration of calmodulin but not with that of Ca2+. Kinetic analysis of this inhibition reveals that the proteins inhibit these enzyme activities in a competitive fashion with calmodulin. The proteins bind to calmodulin on a calmodulin coupled-agarose affinity column in the presence of Ca2+. It is suggested that endogenous basic proteins interact with calmodulin and may modulate intracellular regulation by calmodulin. 相似文献
15.
16.
G L Mendz W J Moore P R Carnegie 《Biochemical and biophysical research communications》1982,105(4):1333-1340
Myelin basic proteins from human, bovine, porcine, rabbit and chicken central nervous systems were examined in aqueous solutions by proton n.m.r. at 400 MHz. Species comparisons and other techniques led to assignments of resonances to specific amino-acid residues. Titration effects associated with aspartic-acid sidechains were effective in identifying adjacent residues. Nuclear Overhauser difference spectra showed that the reverse turn previously suggested for the conformation of an isolated encephalitogenic nonapeptide (guinea-pig determinant) occurred also in the protein, thus supporting the concept of a special low-energy conformation associated with biological activity. The central region of the protein contains methyl groups in aliphatic sidechains with resonances having chemical shifts characteristic of strong shielding effects, thus supporting the idea that less extended secondary and tertiary structures occur in this region. 相似文献
17.
W H Thomas U Weser K Hempel 《Hoppe-Seyler's Zeitschrift für physiologische Chemie》1977,358(10):1345-1352
The structures of two biologically different myelin proteins, A1 from the central nervous system and P2 from the peripheral nervous system, were investigated. Both proteins were isolated from nerve tissues. Conformational changes in the homogeneous proteins were examined in aqueous solutions by means of circular dichroism measurements. The secondary structures of both proteins proved to be very stable between pH 2.5 and pH 11.7. Unlike the P2 protein, the A1 protein is stable up to pH 13 without detectable conformational changes. The stereochemistry of the polypeptide chains of both proteins is markedly different in the presence of urea. While the value of theta222 for the A1 protein changes linearly with increasing urea concentration, a sigmoidal curve was obtained for the P2 protein. The observed differences in the dichroic properties of the basic myelin proteins A1 and P2 indicate the possibility of further structure - function correlations. 相似文献
18.
William R. Gilbert Margaret M. Garwood Daya Agrawal Robert E. Schmidt Harish C. Agrawal 《Neurochemical research》1982,7(12):1495-1506
The immunoblot technique permits the visualization of proteins following their separation on acrylamide gels, transfer to cellulose nitrate sheets and subsequent staining with antiserum. We have utilized this technique to demonstrate the presence of four basic proteins in rat PNS myelin with molecular weights of 21K, 18K, 17K, and 14K. Similarly, we demonstrated the presence of two basic proteins in rabbit PNS myelin (molecular weights of 21K and 18K). Exposure of the immunostained cellulose nitrate strips to X-ray film revealed the phosphorylation of four and two basic proteins in rat and rabbit PNS myelin, respectively. These basic proteins were present in the CNS myelin of the two species and were also phosphorylated. Because of the sensitivity of the immunoblot technique, it was also possible for us to visualize the P2 protein in both rat and rabbit PNS myelin. 相似文献
19.
Examination of 15-day-old rabbit brain myelin proteins by sodium dodecyl sulfate-slab gel electrophoresis revealed the presence of a basic protein with a molecular weight of 21,000 (21K protein) which was not previously reported in this species. This protein exhibited characteristic bluish green color with amido black and gave an amino acid composition strikingly similar to large basic protein (LBP). It formed a line of identity with LBP when diffused against antiserum to chicken brain basic protein. The concentration of LBP (18.9 micrograms/mg of dry myelin) is 6-fold greater than that of the 21K protein(3.31 micrograms/mg of dry myelin) in rabbit brain myelin. After the intracerebral injection of [32P]orthophosphoric acid, both LBP and 21K protein were found to be phosphorylated. [32P]Phosphate in the purified preparations of these proteins was covalently linked by phosphoester bonds to serine and threonine residues. The specific radioactivity of the 21K protein (84,693 cpm/mg of protein) was not significantly higher than LBP (69,797 cpm/mg of protein). 相似文献
20.
The delayed-type hypersensitivity (DTH) response in mice immunized with autologous spinal cord homogenate or purified myelin basic protein (MBP) was measured by the125I-UdR uptake ear assay. Mice were tested for DTH responses with MBP preparations from different species and with synthetic peptides. The 114–122 and 68–84 peptide regions appear to be major determinants for inducing and eliciting DTH in the mice which are susceptible to allergic encephalomyelitis.Special Issue dedicated to Dr. Elizabeth Robez-Einstein.This investigation was supported by Grant No. 1256-B-3 and RG 1197-B7 from the National Multiple Sclerosis Society, N.Y. and a grant from The Margaret T. Biddle Foundation. D.S.L. is a Scholar of the Leukemia Society of America, Inc. 相似文献