title: Pirh2 interacts with and ubiquitylates signal recognition particle receptor beta subunit.
abstract: Pirh2 is a RING finger type ubiquitin ligase which ubiquitylates various proteins including p53, p27(Kip1), HDAC1, and epsilon-COP. In this study, we identified signal recognition particle receptor beta subunit (SRbeta), an integral membrane protein of the endoplasmic reticulum (ER), as a novel Pirh2-interacting protein by yeast two-hybrid screening. We confirmed that Pirh2 interacted with SRbeta in mammalian cells. An immunofluorescent staining revealed that Pirh2 colocalized with SRbeta in the ER. Pirh2 poly-ubiquitylated SRbeta in an intact RING finger domain-dependent manner in vivo and in vitro. Unexpectedly, different from other Pirh2 substrates, neither overexpression of Pirh2 nor depletion of cellular Pirh2 affected SRbeta protein stability. Pirh2 preferentially utilized lysine residues 6 and 29 of the ubiquitin to mediate the formation of polyubiquitin chains on SRbeta. These results suggest that Pirh2 may regulate SRbeta function by mediating poly-ubiquitylation of SRbeta without affecting the stability of SRbeta protein per se.
authors.affiliation: Department of Biochemistry 1, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Abe
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hattori
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Isobe
authors.forename: Kyoko
authors.initials: K
authors.lastname: Kitagawa
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Oda
authors.forename: Chiharu
authors.initials: C
authors.lastname: Uchida
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kitagawa
mesh_terms: D000818:Animals; D019556:COS Cells; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005818:Genetic Engineering; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D008239:Lysine / Q000737:chemistry; D008565:Membrane Proteins / Q000378:metabolism*; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D021122:Protein Subunits / Q000378:metabolism; D051381:Rats; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D008565:Membrane Proteins; D021122:Protein Subunits; C035026:SRPRA protein, human; D025801:Ubiquitin; C485369:RCHY1 protein, human; C577621:Rchy1 protein, rat; D044767:Ubiquitin-Protein Ligases; D008239:Lysine