Related Experiment Video
Updated: Jun 6, 2026

Assay Development for High Content Quantification of Sod1 Mutant Protein Aggregate Formation in Living Cells
Published on: October 4, 2017
ALS-linked mutant superoxide dismutase 1 (SOD1) alters mitochondrial protein composition and decreases protein import
Quan Li1, Christine Vande Velde, Adrian Israelson
1Department of Neurology, Hope Center for Neurological Disorders, The Washington University School of Medicine, St Louis, MO 63110, USA.
Abstract:
Mutations in superoxide dismutase 1 (SOD1) cause familial ALS. Mutant SOD1 preferentially associates with the cytoplasmic face of mitochondria from spinal cords of rats and mice expressing SOD1 mutations. Two-dimensional gels and multidimensional liquid chromatography, in combination with tandem mass spectrometry, revealed 33 proteins that were increased and 21 proteins that were decreased in SOD1(G93A) rat spinal cord mitochondria compared with SOD1(WT) spinal cord mitochondria. Analysis of this group of proteins revealed a higher-than-expected proportion involved in complex I and protein import pathways. Direct import assays revealed a 30% decrease in protein import only in spinal cord mitochondria, despite an increase in the mitochondrial import components TOM20, TOM22, and TOM40. Recombinant SOD1(G93A) or SOD1(G85R), but not SOD1(WT) or a Parkinson's disease-causing, misfolded α-synuclein(E46K) mutant, decreased protein import by >50% in nontransgenic mitochondria from spinal cord, but not from liver. Thus, altered mitochondrial protein content accompanied by selective decreases in protein import into spinal cord mitochondria comprises part of the mitochondrial damage arising from mutant SOD1.
Related Concept Videos
Translocation of Proteins into the Mitochondria
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Mitochondrial Protein Sorting
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
ATP Synthase: Mechanism
Mitochondrial Membranes
Protein Import into the Peroxisomes
Peroxisomal Protein Import:
Peroxisomes lack the genetic machinery required to code for their own proteins. Hence, most peroxisomal membrane, lumenal and transmembrane proteins are synthesized in the cytoplasm or ER and transported to the peroxisome...
Mitochondrial Precursor Proteins
Most of the mitochondrial precursors...

