title: Multiple gamma-glutamylation: a novel type of post-translational modification in a diapausing Artemia cyst protein.
abstract: A highly hydrophilic, glutamate-rich protein was identified in the aqueous phenol extract from the cytosolic fraction of brine shrimp (Artemia franciscana) diapausing cysts and termed Artemia phenol soluble protein (PSP). Mass spectrometric analysis revealed the presence of many protein peaks around m/z 11,000, separated by 129 atomic mass units; this value corresponds to that of glutamate, which is strongly suggestive of heterogeneous polyglutamylation. Polyglutamylation has long been known as the functionally important post-translational modification of tubulins, which carry poly(L-glutamic acid) chains of heterogeneous length branching off from the main chain at the gamma-carboxy groups of a few specific glutamate residues. In Artemia PSP, however, Edman degradation of enzymatic peptides revealed that at least 13, and presumably 16, glutamate residues were modified by the attachment of a single L-glutamate, representing a hitherto undescribed type of post-translational modification: namely, multiple gamma-glutamylation or the addition of a large number of glutamate residues along the polypeptide chain. Although biological significance of PSP and its modification is yet to be established, suppression of in vitro thermal aggregation of lactate dehydrogenase by glutamylated PSP was observed.
authors.affiliation: Bioscience Course, Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Nishi-Ku, Niigata 950-2181, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Yuka
authors.initials: Y
authors.lastname: Ikeda
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kanzawa
authors.forename: Mika
authors.initials: M
authors.lastname: Sakamoto
authors.forename: Mina
authors.initials: M
authors.lastname: Goto
authors.forename: Susumu
authors.initials: S
authors.lastname: Tsunasawa
authors.forename: Toshio
authors.initials: T
authors.lastname: Uchiumi
authors.forename: Shoji
authors.initials: S
authors.lastname: Odani
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001156:Artemia / Q000378:metabolism*; D008969:Molecular Sequence Data; D011099:Polyglutamic Acid / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D011506:Proteins; D011994:Recombinant Proteins; D011099:Polyglutamic Acid