title: Carbonic anhydrase I is recognized by an SOD1 antibody upon biotinylation of human spinal cord extracts.
abstract: We recently reported the presence of a novel 32 kDa protein immunoreactive to a copper, zinc superoxide dismutase (SOD1) antibody within the spinal cord of patients with amyotrophic lateral sclerosis (ALS). This unique protein species was generated by biotinylation of spinal cord tissue extracts to detect conformational changes of SOD1 specific to ALS patients. To further characterize this protein, we enriched the protein by column chromatography and determined its protein identity by mass spectrometry. The protein that gave rise to the 32 kDa species upon biotinylation was identified as carbonic anhydrase I (CA I). Biotinylation of CA I from ALS spinal cord resulted in the generation of a novel epitope recognized by the SOD1 antibody. This epitope could also be generated by biotinylation of extracts from cultured cells expressing human CA I. Peptide competition assays identified the amino acid sequence in carbonic anhydrase I responsible for binding the SOD1 antibody. We conclude that chemical modifications used to identify pathogenic protein conformations can lead to the identification of unanticipated proteins that may participate in disease pathogenesis.
authors.affiliation: Department of Neuroscience, California Pacific Medical Center Research Institute, 475 Brannan Street, San Francisco, CA 94107, USA; E-Mail: lumz@cpmcri.org (M.L.).
authors.forename: Jian
authors.initials: J
authors.lastname: Liu
authors.forename: Armin
authors.initials: A
authors.lastname: Akhavan
authors.forename: Mengde
authors.initials: M
authors.lastname: Lu
authors.forename: Arie
authors.initials: A
authors.lastname: Gruzman
authors.forename: Vishwanath R
authors.initials: VR
authors.lastname: Lingappa
authors.forename: Jiyan
authors.initials: J
authors.lastname: An
authors.forename: Robert
authors.initials: R
authors.lastname: Bowser
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000201:enzymology / Q000276:immunology; D019921:Biotinylation; D024401:Carbonic Anhydrase I / Q000276:immunology*; D006801:Humans; D007118:Immunoassay; D040901:Proteomics; D013116:Spinal Cord / Q000201:enzymology* / Q000276:immunology; D013482:Superoxide Dismutase / Q000276:immunology*; D000072105:Superoxide Dismutase-1
chemical_list: C000606290:SOD1 protein, human; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D024401:Carbonic Anhydrase I