Basis of microheterogeneity of myelin basic protein.

Chou, Frank C.‐H.; Chou, C H; Shapira, Raymond; Kibler, Robert F.

doi:10.1016/s0021-9258(17)33540-8

Cited by 200 publications

(46 citation statements)

References 15 publications

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“…These immunochemical findings may reflect a special role for peptide 43-88 or adjacent region of BP in the host immune response to BP, the metabolism of BP, and the alignment of BP in the myelin membrane. In the molecular region of residues 64-121 there occur the major encephalitogenic sites for the rabbit (13), Lewis rat (14), and guinea pig (11), a substrate for in vivo phosphorylation (26) and glycosylation (56) at threonine-97, and a methylated arginine at residue 106 (57). The relationship of T-lymphocyte responsitivity to peptide 43-88 to the induction of EAE in rats has also been documented (33).…”

Section: Discussionmentioning

confidence: 99%

“…The lack of inhibition by BP of the reaction between the two antisera and peptide 43-88 provides proof that intact BP in solution and not previously exposed to the conditions of radioiodination or linked to Sepharose is also incapable of furnishing an accessible antigenic site for attachment of the antibodies raised to peptide 43-88. The failure of the BP-immunoadsorbent, prepared with a mixture of microheterogeneous BP components 1-4 (26,39), to remove antibodies to peptide 43-88 suggests that this inaccessibility is likely to be present in each of the microheterogeneous fractions as they are attached to Sepharose.…”

Section: Discussionmentioning

confidence: 99%

“…Bovine BP and guinea pig BP were purified by extraction and cationexchange chromatography (16). The last major peak (16,26), designated as component 1, 2 to elute from the CM-cellulose was used as the starting material for fragmentation. Components 1-4 from bovine BP were mixed and used for preparation of the BP solid-phase immunoadsorbent.…”

mentioning

confidence: 99%

“…Electrophoresis of the individual BP components on polyacrylamide gels in acetic acid-urea (27) and at pH 4.3 (28) showed essentially one band. Combining the major components of bovine BP for use in solid-phase immunoadsorbence seemed justified since previous studies (26) have shown that these components probably do not differ in their amino acid sequence but differ because of modification by phosphorylation and/or deamidation reasonably restricted to specific sites in the polypeptide chain.…”

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confidence: 99%

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Molecular internalization of a region of myelin basic protein

Whitaker¹,

Chou²,

Chou³

et al. 1977

The Journal of Experimental Medicine

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The conformation of myelin encephalitogenic or basic protein (BP) was investigated with a double-antibody radioimmunoassay by studying the reaction of BP or its fragments with antibodies produced in two rabbits against peptide 43-88 linked to rabbit serum albumin. Both antisera reacted well with peptide 43-88 but showed little or no reaction with BP. Absorption of these antisera with a BP-immunoadsorbent did not remove the antibody activity against peptide 43-88. Within the region of peptide 43- 88 it was shown that peptides 68-88 and 79-88 gave an equivalent or better reaction than peptide 43-88, whereas peptides 43-67 and 64-73 had very little reactivity. In the BP fragments containing region 43-88, peptide 1-88 showed the best reactivity, peptide 20-166 showed minimal reactivity, while peptide 1-115 showed none. These data document the internal position of at least a portion of peptide 43-88 and all of residues 79-88 in the BP molecule. The much greater reactivity of peptide 1-88 as compared to peptide 1-115 suggests that the region or a portion of the region of BP containing residues 89- 115 participates in the conformational alignment of BP restricting access to peptide 79-88. After absorption with BP, neither of the antisera prepared to peptide 43-88 reacted with PNS myelin in fixed tissue sections but continued to react with CNS myelin in similarly treated sections. The present findings demonstrate the need to consider the role of shielded antigenic determinants in the investigation of antigens or of immune responses.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Molecular internalization of a region of myelin basic protein

Whitaker¹,

Chou²,

Chou³

et al. 1977

The Journal of Experimental Medicine

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“…All other 111 reagents were of analytical or HPLC grade. The bovine brain MBP charge isoform CI (MBP, C1) [17] was providcd by Drs. R. Zand and C. Caamafio (Biophysics l)ivision, Institute of Science and Technology.…”

Section: Methodsmentioning

confidence: 99%

Carboxylmethylation affects the proteolysis of myelin basic protein by Staphylococcus aureus V8 proteinase

Sellinger

Wolfson

1991

Biochimica et Biophysica Acta (BBA) - Protein Structure and Mol

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Bovine myelin basic protein (MBP), charge isoform 1 (C1) was carboxylmethylated by the enzyme D-aspartyl/L-isoaspartyl protein methyltransferase (EC. 2.1.1.77) and the carboxylmethylated protein was subjected to proteolysis by sequencing grade staphylococcal V8 proteinase at pH 4.0 to identify its carboxylmethylated modified aspartate and/or asparagine residues which are recognized by this methyltransferase. Native MBP, C1 was treated similarly and the proteolysis products were compared, using electrophoretic, chromatographic and amino acid sequencing techniques. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) revealed differences in the kinetics of proteolysis between the native and the carboxylmethylated MBP, C1 which were confirmed using HPLC. Partial sequencing of the native and carboxylmethylated fragments eluting at about 29 min (P29) revealed cleavage of native MBP, C1 at Gly-127-Gly-128 and of the carboxylmethylated MBP, C1 at Phe-124-Gly-125. Additional evidence including tryptic subdigestion of carboxylmethylated P29 disclosed the following partial sequence for this peptide: Gly-Tyr-Gly-Gly-Arg-Ala-Ser-Asp-Tyr-Lys-Ser-Ala-His-Lys-Gly-Leu-Lys- Gly-His-Asp-Ala-Gln-Gly-Thr-Leu-Ser-Lys-Ileu-Phe-Lys-. This sequence matches MBP residues 125-154. As a result of these findings, Asp-132 and Asp-144 were identified as two of the modified (isomerized or racemized) methyl-accepting L-aspartates in MBP. The results of the proteolysis experiments wherein the sequencing grade staphylococcal V8 proteinase was used at the rarely tested pH of 4.0, rather than at its commonly tested pH of 7.8, also disclose that the proteinase totally failed to recognize and hence cleave the two Glu-X bonds (Glu-82-Asn-83 and Glu-118-Gly-119) of MBP, preferring to cleave the protein at a number of hitherto unreported sites.

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Highly deiminated isoform of myelin basic protein from multiple sclerosis brain causes fragmentation of lipid vesicles

et al. 1999

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Myelin basic protein (MBP) occurs as a number of charge isomers due to phosphorylation, deamidation, and deimination of arginine to citrulline. All of these modifications decrease the net positive charge of the protein and its ability to cause aggregation of negatively charged lipid vesicles. This is used as a model system for the ability of MBP to cause adhesion of the cytosolic surfaces of myelin. Therefore, the effect of two deiminated forms of MBP on lipid vesicles was compared with that of the unmodified, most positively charged isomer, C1, to determine how loss of positively charged arginines would affect the function of MBP. The deiminated forms were the isomer isolated from normal human brains, in which only 6 Arg are deiminated to citrulline (MBP-Cit(6)), and an isomer isolated from the brain of a patient who died with acute, fulminating multiple sclerosis (Marburg type), in which 18 of the 19 Arg were deiminated (MBP-Cit(18)). Whereas C1 caused aggregation of lipid vesicles, resulting in an increase in absorbance due to light scattering, MBP-Cit(18) caused a decrease in absorbance of the lipid vesicles. Size exclusion chromatography and negative staining electron microscopy showed that this was due to fragmentation of the large multilayered vesicles into much smaller vesicles. MBP-Cit(6) caused less aggregation of lipid vesicles than did C1. However, no fragmentation of the vesicles into smaller ones in the presence of C1 and MBP-Cit(6) was detected by size exclusion chromatography or electron microscopy. The membrane fragmentation caused by MBP-Cit(18) is dramatically different from the effects of other forms of MBP from normal brain and may indicate a pathogenic effect of this charge isomer, which may have contributed to the severity of the Marburg type of multiple sclerosis. Alternatively, the deimination may have been a secondary effect resulting from the disease process. Regardless of the role of MBP-Cit(18) in multiple sclerosis, the effect of this modification indicates that, when most of the arginines of MBP are modified to an uncharged amino acid, the protein acquires properties similar to an apolipoprotein; thus, it may take up an amphipathic structure when bound to lipid. A partly amphipathic character may also be related to the role of MBP-Cit(6) in normal immature myelin, where it is the predominant charge isomer.

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Basis of microheterogeneity of myelin basic protein.

Cited by 200 publications

References 15 publications

Molecular internalization of a region of myelin basic protein

Molecular internalization of a region of myelin basic protein

Carboxylmethylation affects the proteolysis of myelin basic protein by Staphylococcus aureus V8 proteinase

Highly deiminated isoform of myelin basic protein from multiple sclerosis brain causes fragmentation of lipid vesicles

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