title: Mass spectrometric peptide analysis of 2DE-separated mouse spinal cord and rat hippocampus proteins suggests an NGxG motif of importance for in vivo deamidation.
abstract: Asparagine deamidation is a common nonenzymatic post-translational modification comprising the conversion of asparaginyl residues to aspartyl and isoaspartyl residues, respectively. As a result an additional negative charge is introduced that can affect the tertiary structure as well as the biological activity of a protein. Since deamidation reduces the protein's pI value, differentially deamidated forms of a protein can be separated in 2D gels. We have analyzed a dataset of 430 protein spots from 2D gels that contained mouse spinal cord proteins and estimated that roughly 10% of the spots in a Coomassie-stained gel derive from in vivo deamidation at particular asparaginyl residues. Several of the deamidated protein forms, e.g. tropomodulin-2, V-type proton ATPase subunit B, and protein disulfide-isomerase A3 were also found in 2D gels of proteins extracted from rat hippocampus. All identified deamidation sites contained a glycine residue on the carboxyl side of the asparaginyl residue. Strikingly, a second glycine residue at the +3 position was found in the majority of the deamidated peptides. We propose that the NGxG motif confers exceptional susceptibility to in vivo asparagine deamidation.
authors.affiliation: Core Facility Proteome Analysis, University Medicine Rostock, Rostock, Germany. stefan.mikkat@med.uni-rostock.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Mikkat
authors.forename: Timo
authors.initials: T
authors.lastname: Kischstein
authors.forename: Michael
authors.initials: M
authors.lastname: Kreutzer
authors.forename: Michael O
authors.initials: MO
authors.lastname: Glocker
mesh_terms: D000577:Amides / Q000032:analysis; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001216:Asparagine / Q000032:analysis*; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013116:Spinal Cord / Q000737:chemistry*
chemical_list: D000577:Amides; D011506:Proteins; D001216:Asparagine