Premium
The DM20 Protein of Myelin: Intracellular and Surface Expression Patterns in Transfectants
Author(s) -
Timsit S.,
Sinoway M. P.,
Levy L.,
Allinquant B.,
Stempak J.,
Staugaitis S. M.,
Colman D. R.
Publication year - 1992
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.1471-4159.1992.tb10072.x
Subject(s) - proteolipid protein 1 , myelin , endoplasmic reticulum , biology , intracellular , microbiology and biotechnology , myelin proteolipid protein , extracellular , myelin basic protein , central nervous system , neuroscience
DM20 is an abundant CNS myelin‐specific protein whose role in myelinogenesis is unknown. We have cloned the DM20 cDNA from adult mouse brain total RNA using the polymerase chain reaction and expressed it in HeLa cells. DM20, detected by immunofluorescence in stable transfectants, is present in some cells in large, intensely fluorescent intracellular clumps that probably represent elements of the rough endoplasmic reticulum and Golgi apparatus. Frequently, intense DM20 fluorescence could be detected at the plasma membrane. These findings are consistent with previous studies demonstrating that an intracellular “pool” of DM20 and its larger isoform, proteolipid protein, exists and that a substantial lag occurs between synthesis and insertion of these proteins into the expanding myelin membrane. Permanent DM20 expressors in contact with one another do not display any ultrastructural rearrangements at regions of cell–cell contact, in contrast to what we have previously reported for P 0 , a PNS‐specific protein shown to mediate adhesion of the extracellular faces of the Schwann cell during PNS myelinogenesis. We believe that these results indicate that if DM20 is indeed an adhesion molecule, this property is likely to be significantly more subtle than P 0 ‐mediated adhesion.