In humans, mutation of glycine 93 to alanine of Cu<sup>++</sup>/Zn<sup>++</sup> superoxide dismutase type-1 (SOD1-G93 A) has been associated to some familial cases of Amyotrophic Lateral Sclerosis (ALS).
It was also revealed that by reducing the disulfide bond and causing a decrease in the structural stability, the amyloid fibril formation of a familial mutant SOD1 G93A was accelerated even under physiological conditions.
In conclusion, there are commonalities of findings in sporadic ALS patients and presymptomatic SOD1-G93A transgenic mice and these implicate inadequate proteasome function in the pathogenesis of both familial and sporadic ALS.
The superoxide dismutase 1(G93A G1H) (SOD1(G93A G1H)) transgenic mouse is a model of familial human amyotrophic lateral sclerosis (ALS) that has progressive neurodegeneration within the spinal cord and brainstem.
No increase in Hsp70 occurred in motor neurons after exposure to excitotoxic glutamate or expression of mutant SOD-1 with a glycine--> alanine substitution at residue 93 (G93A), nor was Hsp70 increased in spinal cords of G93A SOD-1 transgenic mice or sporadic or familial ALS patients.