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A New Form of Myelin Basic Protein Found in Human Brain
Author(s) -
Deibler Gladys E.,
Krutzsch Henry C.,
Kies Marian W.
Publication year - 1986
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.1471-4159.1986.tb00743.x
Subject(s) - myelin basic protein , chemistry , myelin , elution , chromatography , amino acid , polyacrylamide gel electrophoresis , electrophoresis , biochemistry , high performance liquid chromatography , fraction (chemistry) , biology , enzyme , neuroscience , central nervous system
Human myelin basic protein was subjected to ionexchange chromatography at high pH to separate the differently charged components. Polyacrylamide gel electrophoretic patterns of the fractions showed that the less basic fractions 3, 4, and 5 contained significant amounts of a protein somewhat smaller than the more common 18.5‐kDa form. Fraction 3 consisted of approximately equal amounts of this smaller polypeptide and component 3, the 18.5‐kDa form found in other mammalian myelin basic protein preparations. The two proteins in fraction 3 were separated by fast protein liquid chromatography. Both have blocked N termini and identical C termini (‐Met‐Ala‐Arg‐Arg). When the tryptic digests of the two proteins were fractionated by HPLC, the elution profiles were similar, except that four peaks found in the chromatogram of the larger protein were missing from the chromatogram of the smaller one. In addition, an extra peak was found in the elution pattern of the latter chromatogram. Amino acid analysis of the individual tryptic peptides indicated that the smaller protein lacked residues 106–116 (‐Gly‐Arg‐Gly‐Leu‐Ser‐Leu‐Ser‐Arg‐Phe‐Ser‐Trp‐). The deleted portion corresponds exactly to the amino acid sequence encoded by exon 5 of the mouse basic protein gene. This new form of myelin basic protein has a molecular weight of 17,200, calculated from its amino acid composition.