SOD1 (superoxide dismutase 1, soluble), also known as ALS. The protein binds copper and zinc ions and is one of two isozymes responsible for destroying free superoxide radicals in the body. The encoded isozyme is a soluble cytoplasmic protein, acting as a homodimer to convert naturally-occuring but harmful superoxide radicals to molecular oxygen and hydrogen peroxide. The other isozyme is a mitochondrial protein. Mutations in this gene have been implicated as causes of familial amyotrophic lateral sclerosis (ALS), a progressive degenerative disease of motor neurons. Rare transcript variants have been reported for this gene.