The defining feature of ALS is the death of both upper and lower motor neurons in the motor cortex of the brain, the brain stem, and the spinal cord. Prior to their destruction, motor neurons develop proteinaceous inclusions in their cell bodies and axons. This may be partly due to defects in protein degradation. These inclusions often contain ubiquitin, and generally incorporate one of the ALS-associated proteins: SOD1, TAR DNA binding protein (TDP-43, or TARDBP), or FUS.
Read more about this topic: Amyotrophic Lateral Sclerosis