May play a role in compacting or stabilizing the myelin sheath, possibly by binding the negatively charged acidic phospholipids of the cytoplasmic membrane. Present in the major dense line of CNS myelin. Isoform 5 may be differentially localized in the oligodendrocytes or perinuclear region. Isoform 2, 4, 5 and 6 are highly enriched in myelin. Isoform 1 and 3 are not enriched in mylein. Expressed predominantly in oligodendrocytes, in CNS myelin of the cerebrum and spinal cord. No expression seen in sciatic nerve. Expression in different brain regions during development is correlated with the progression of myelin formation. Isoform 5 seems to be the most abundant spliced form expressed during development. Expressed at P7 in optic nerve, at this time point, the first compact myelin is formed. At P9 abundantly expressed in the optic nerve.