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An Antibody Specific for Component 8 of Myelin Basic Protein from Normal Brain Reacts Strongly with Component 8 from Multiple Sclerosis Brain
Author(s) -
McLaurin J.,
Hashim G.,
Moscarello M. A.
Publication year - 1992
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1992.tb08455.x
Subject(s) - multiple sclerosis , component (thermodynamics) , myelin , myelin basic protein , antibody , myelin sheath , neuroscience , chemistry , central nervous system , immunology , biology , physics , thermodynamics
Myelin basic protein (MBP) consists of several components or charge isomers (C‐1 through C‐8) generated by one or a combination of posttranslational modifications. One of these, C‐8, has been shown to contain citrulline (Cit) at defined sites formed by deimination of six arginyl residues. This unusual modification has allowed us to raise antibodies specific for this charge isomer only. To do this, a synthetic peptide, Gly‐Cit‐Cit‐Cit‐Cit, was coupled to keyhole limpet hemocyanin and injected into rabbits. The antibodies so generated reacted only with C‐8 and not with any of the other charge isomers. A second antibody fraction was raised against the synthetic peptide ACitHGFLPCitHR naturally occurring between residues 24 and 33 of C‐8 (all other charge isomers contain R instead of Cit at positions 25 and 31). These antibodies preferred C‐8 but reacted with the other charge isomers, to the extent of ∼25–30% of the reactivity shown with C‐8. In studies with C‐8 from multiple sclerosis (MS) MBP, much greater reactivity was obtained with these antibodies when compared with their reactivity with C‐8 from normal MBP. Because the total number of Cit residues in C‐8 from MS and normal MBP is the same, the difference in reactivity may be related to structural factors. The antibodies raised with the tetra‐Cit peptide were reacted with three pairs of synthetic peptides: 24 ARHGFLPRHR 33 and ACitHGFLPCitHR; 120 GQRPGFGYGGRAS 132 and GQCitPGFGYGGCitAS; and 157 GGRDSRSGSPMARR 170 and GGCitDSRSGSPMACitR. They reacted only with the Cit‐containing peptides in the order 157–170 > 120–130 > 24–33. Because all three peptides contained two Cit residues, the greater reactivity of 157–170 suggested structural factors may modulate the activity. With S49, an antibody raised against peptide 69 GSLPQKSQ‐RSQDEN 84 (rat sequence), a region in which Cit was not found and therefore is identical for both C‐1 and C‐8, showed greater reaction with C‐1 than C‐8, further supporting a role for conformational factors. Because the major difference between C‐1 and C‐8 is the presence of Cit in the later, conformational changes in this region of MBP must have been induced by Cit located even at some distance in the linear sequence of amino acids.