title: Accumulation and turnover of the classical Folch-Lees proteolipid proteins in developing and adult rat brain.
abstract: The turnover of classical Folch-Lees proteolipid proteins was studied after administration of [2,3-3H]tryptophan to both developing and adult rat brain. The animals were killed from 2h to 250 days after subcutaneous injections of [3H]tryptophan. The measured specific radioactivity in developing brain attained maximum value 24h after the administration of label, whereas the total radioactivity per brain reached a maximum 21 days after injection. The half-life of proteolipid protein from the measured specific radioactivity was 7-20 days, depending on the time-points used for the calculation, whereas calculation from total radioactivity between 28-77 and 91-257 days gave half-lives of 35-40 and 188 days respectively. In contrast, in animals injected at 40 days of age, the half-life from the whole-brain-radioactivity data was 188 days. The problem of the recycling of radioactivity for the synthesis of myelin proteins from either a general or a discrete amino acid pool is discussed.
mesh_terms: D000367:Age Factors; D000818:Animals; D001921:Brain / Q000254:growth & development / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006207:Half-Life; D008074:Lipoproteins / Q000378:metabolism*; D051381:Rats
chemical_list: D008074:Lipoproteins