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PROTEOLIPID PROTEIN: SYNTHESIS AND ASSEMBLY INTO QUAKING MOUSE MYELIN
Author(s) -
Greenfield S.,
Williams N. I.,
White M.,
Brostoff S. W.,
Hogan E. L.
Publication year - 1979
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.1471-4159.1979.tb02275.x
Subject(s) - myelin , proteolipid protein 1 , glycine , cerebroside , biochemistry , biology , myelin basic protein , chemistry , central nervous system , endocrinology , amino acid
The incorporation of radioactive glycine into the major myelin proteolipid protein isolated from whole brain and from purified myelin of Quaking mice and normal littermates was compared. In a typical experiment, four Quaking mice and four littermate controls were injected intracranially with 250 μCi [2‐ 3 H]glycine and 25 μCi [U‐ 14 C]glycine respectively. Three hours later, the eight mice were killed and their brains combined. Equivalent portions were taken for (1) chloroform‐methanol (2:1) extraction followed by ether precipitation of proteolipid from the brain and (2) myelin preparation. The 3H / 14 C ratios for the microsomes:, the major myelin proteolipid as well as the other non‐myelin proteolipids extracted from whole brain was approx 3.0. while the 3 H/ 14 C ratio for proteolipid protein in myelin was near 0.4. These findings were consistent for ages studied between 18 and 90 days. The results indicate that the synthesis of the major myelin proteolipid protein in the whole brain of Quaking mouse, as seen previously in our studies on basic protein, proceeds at a normal rate relative to microsomes but its incorporation into myelin is depressed. A working hypothesis of myelin membrane assembly is presented to account for the defect in the incorporation of these proteins into Quaking myelin.