title: Targeted mass spectrometric analysis of N-terminally truncated isoforms generated via alternative translation initiation.
abstract: Alternative translation initiation is a mechanism whereby functionally altered proteins are produced from a single mRNA. Internal initiation of translation generates N-terminally truncated protein isoforms, but such isoforms observed in immunoblot analysis are often overlooked or dismissed as degradation products. We identified an N-terminally truncated isoform of human Dok-1 with N-terminal acetylation as seen in the wild-type. This Dok-1 isoform exhibited distinct perinuclear localization whereas the wild-type protein was distributed throughout the cytoplasm. Targeted analysis of blocked N-terminal peptides provides rapid identification of protein isoforms and could be widely applied for the general evaluation of perplexing immunoblot bands.
authors.affiliation: FTN Institute, 1147 Mariner Cove, Sugar Land, TX 77498, USA. rkobayash@gmail.com
authors.forename: Ryuji
authors.initials: R
authors.lastname: Kobayashi
authors.forename: Rebecca
authors.initials: R
authors.lastname: Patenia
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ashizawa
authors.forename: Jody
authors.initials: J
authors.lastname: Vykoukal
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D010442:Peptide Chain Initiation, Translational; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D004268:DNA-Binding Proteins; C489560:DOK1 protein, human; D010750:Phosphoproteins; D020033:Protein Isoforms; D016601:RNA-Binding Proteins