title: Identification of two isoforms of Dsk2-related protein XDRP1 in Xenopus eggs.
abstract: The budding yeast UbL-UBA protein Dsk2 has a UbL domain at its N-terminus and a UBA domain at its C-terminus, and thus functions as a shuttle protein in the ubiquitin-proteasome pathway. In this report we describe two isoforms of Xenopus Dsk2-related protein, XDRP1L and XDRP1S. Difference of the two proteins in sequence was that the UbL domain of XDRP1S lacks 15 residues in the middle part of that of XDRP1L. Both XDRP1L and XDRP1S were expressed in Xenopus eggs. XDRP1L and XDRP1S bound to polyubiquitinated proteins via their UBA domains. XDRP1L also bound to the proteasome via its UbL domain, whereas the XDRP1S UbL domain was less likely to bind to the proteasome. Instead, XDRP1S not XDRP1L bound to monomeric cyclin A and prevented its degradation. The existence of such Dsk2-isoforms in Xenopus eggs suggests that the shuttling function via the UbL-UBA protein Dsk2 is evolutionally conserved across species.
authors.affiliation: Department of Molecular Biology, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Kanae
authors.initials: K
authors.lastname: Tanaka
authors.forename: Minoru
authors.initials: M
authors.lastname: Funakoshi
authors.forename: Kazue
authors.initials: K
authors.lastname: Inoue
authors.forename: Hideki
authors.initials: H
authors.lastname: Kobayashi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014452:Ubiquitins / Q000737:chemistry* / Q000378:metabolism*; D029867:Xenopus Proteins / Q000737:chemistry* / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D018797:Cell Cycle Proteins; C100415:DSK2 protein, S cerevisiae; D009687:Nuclear Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; D029701:Saccharomyces cerevisiae Proteins; D014452:Ubiquitins; D029867:Xenopus Proteins; C122049:DAPK2 protein, Xenopus; D017346:Protein Serine-Threonine Kinases