DEVELOPMENTAL-STUDY OF PROTEOLIPIDS IN BOVINE BRAIN - A NOVEL PROTEOLIPID AND DM-20 APPEAR BEFORE PROTEOLIPID PROTEIN (PLP) DURING MYELINATION

Abstract: In a developmental study, we have shown that DM‐20 is present before proteolipid protein (PLP) in the fetal bovine cerebral hemispheres. When the white matter appears (27–30 weeks of gestation), the amount of DM‐20 drastically increases. DM‐20 remains the major proteolipid until birth. PLP is detected only 2–4 weeks after the appearance of white matter, that is, more than 4 weeks after the appearance of DM‐20. The early appearance of DM‐20 at the beginning of myelination raises the question of its particular function. In the adult bovine cerebral hemispheres, PLP is the major proteolipid but DM‐20 remains quantitatively important because the PLP/DM‐20 ratio ranges from 1.5 to 1.7. In the same developmental study we have, in the fetal cerebral hemispheres, isolated and characterized a novel proteolipid (apparent Mr 20,000), which appears even before DM‐20 and is not detected in the adult brain. It is structurally related to PLP and DM‐20 because the first 31 N‐terminal amino acid residues are the same. However, in immunoblot. it did not react either with the antitridecapeptide 117–129 antiserum of PLP or with the anti‐C‐terminal hexapeptide antiserum of PLP. Copyright © 1990, Wiley Blackwell. All rights reserved