Isoform 4 of Myelin basic protein

Myelin basic protein (MBP) is a structural component of the myelin sheath that insulates axons in the central and peripheral nervous systems. Isoform 4 is a 186-amino acid variant (UniProt: P02686-4) with a molecular weight of approximately 20 kDa and plays a critical role in maintaining myelin stability and neuronal conduction velocity.

MBP is highly expressed in oligodendrocytes and is essential for myelination, a process central to nervous system development and function. The protein is involved in organizing and stabilizing the compact myelin lamellae that wrap around axons, thereby enabling rapid saltatory conduction of action potentials.

In Alzheimer's disease, this isoform shows significant downregulation in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics: mean log2 fold-change −2.114), consistent with the disease:ad tag indicating downward direction. This reduction may reflect myelin degradation or loss of oligodendrocyte integrity that characterizes AD neuropathology, contributing to the white matter changes and neuronal dysfunction observed in the disease.