FIGURE 2.
Core regions in aggregates of WT and fALS-mutant SOD1 proteins identified by MALDI-TOF mass analysis. SOD1G37R, SOD1G85R, and SOD1G93A indicate aggregates extracted from lumbar spinal cords of the corresponding transgenic mice, whereas the others are SOD1 aggregates prepared from the recombinant proteins with indicated fALS mutations. SOD1 aggregates were treated with Pronase, and the peptides resistant to digestion by Pronase were identified by MALDI-TOF mass spectrometry and mapped on the SOD1 primary sequence. Numbers indicated above the primary sequence of SOD1 (shown as an open bar) represent the amino residue numbers. Identification of mass peaks was performed based upon the observed mass values, and peptides shown as thick bars were further confirmed by MS/MS analysis. Details of peptide identification are summarized in supplemental Table S1 and supplemental Fig. S3, L–O.