Reduced levels of a specific myelin-associated oligodendrocytic basic protein isoform in shiverer myelin

Myelin-associated oligodendrocytic basic protein (MOBP) and myelin basic pr otein (MBP) share many structural similarities. MOBP is synthesised by matu re oligodendrocytes and localised at the major dense line (MDL), suggesting a role in the myelin compaction process. The shiverer mouse, a deletion mu tant of the myelin basic protein (Mbp) gene, has poorly compacted myelin wi th essentially no MDL. in this study we compare the developmental expressio n of the Mobp gene in wild-type and shiverer mice. The significant finding is that one of the two abundant MOBP isoforms, the similar to 20kD species, is poorly incorporated into shiverer myelin. The absence is specific to sh iverer and is not a feature of dysmyelinating mutants with an abnormal intr aperiod line. Our data suggest that incorporation of this MOBP isoform into shiverer myelin may be influenced by the presence of MBP or be a consequen ce of a disrupted MDL.