Scientists have long known that proteins can form harmful clusters in neurodegenerative diseases like Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis (ALS). But a new study by Penn State researchers shows that ‘variant’ complexes of a protein implicated in ALS pathology form in separate pathways, a discovery which may make it easier for drug developers to design therapies to target the more harmful variant.
Superoxide dismutase (SOD1) is an aggregating protein that contributes to ALS development and progression, though it is unclear which biological mechanisms it uses to do this. Mutations in this protein have been implicated in 15-30% of familial ALS cases and 1-2% of spontaneous ALS cases. Normally existing in a two-part dimer, loss of SOD1 copper or zinc ions can cause it to separate into two separate monomers, or units. Monomers can form form a trimer, or three-part form, or aggregate into larger fibrils, which consist of many SOD1 monomers. Previous research showed that the trimer form is toxic to cells. Other research has suggested that the larger aggregate form may actually have a protective function.



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