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Myelin‐Associated Glycoprotein and Other Proteins in Trembler Mice
Author(s) -
Inuzuka Takashi,
Quarles Richard H.,
Heath John,
Trapp Bruce D.
Publication year - 1985
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.1471-4159.1985.tb12885.x
Subject(s) - myelin associated glycoprotein , myelin , sciatic nerve , glycoprotein , myelin basic protein , schwann cell , biology , medicine , endocrinology , chemistry , microbiology and biotechnology , anatomy , central nervous system
The myelin‐associated glycoprotein (MAG) and other myelin proteins were quantitated in homogenates of whole sciatic nerve from adult and 20‐day‐old Trember mice. In the nerves of adult mice, the concentration of MAG was increased from 1.1 ng/μg of total protein in the controls to 1.4 ng/μg protein in the Tremblers. By contrast, the concentrations of P 0 glycoprotein and myelin basic proteins were reduced to 27% and 20% of control levels, respectively. Immunoblots demonstrated that P 2 was also greatly reduced in the Trembler nerves. The specific activity of 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase (CNP) was 65% of the control level. Immunoblot analysis showed that MAG had a higher than normal apparent M r in the sciatic nerves of the Trembler mice, but its apparent M r was normal in the brains of these mutants. In 20‐day‐old Tremblers, the P 0 and myelin basic protein were reduced slightly less to about 40% of the level in the nerves of age‐matched controls. CNP and MAG levels were not significantly different from those in controls, and MAG exhibited a shift toward higher apparent M r similar to that in the adults. The maintenance of high MAG levels despite the severe deficit of myelin, as reflected by the decrease of the major myelin proteins, is consistent with the immunocytochemical localization of MAG in periaxonal Schwann cell membranes, Schmidt‐Lantermann incisures, lateral loops, and the outer mesaxon and its absence from compact myelin. The abnormal form of MAG in the peripheral nervous sytem (PNS) of the Trembler mice may contribute to the pathology in this mutant.