VAPB contains 1 MSP domain and it may play a role in vesicle trafficking.
Defects in VAPB are a cause of proximal adult autosomal dominant spinal muscular atrophy [MIM:182980]; also called late onset spinal muscular atrophy Finkel type. Spinal muscular atrophies are neurodegenerative disorders characterized by degeneration of lower motor neurons, leading to progressive paralysis muscular atrophy. This form is a late adult onset form of the disease (after age 20 years). The patients show a benign course, most of them remaining ambulatory 10 to 40 years after clinical onset.
Cell membrane; Single-pass type IV membrane. Intracytoplasmic membrane; Single-pass type IV membrane protein. Note: Present in the plasma membrane and in intracellular vesicles.