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A palmitoylated RING finger ubiquitin ligase and its homologue in the brain membranes
Author(s) -
Araki Kazuaki,
Kawamura Meiko,
Suzuki Toshiaki,
Matsuda Noriyuki,
Kanbe Daiji,
Ishii Kyoko,
Ichikawa Tomio,
Kumanishi Toshiro,
Chiba Tomoki,
Tanaka Keiji,
Nawa Hiroyuki
Publication year - 2003
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2003.01875.x
Subject(s) - ubiquitin ligase , ubiquitin , ring finger , dna ligase , zinc finger , in vitro , microbiology and biotechnology , biology , ring finger domain , in vivo , biochemistry , chemistry , enzyme , genetics , transcription factor , gene
Ubiquitin (Ub) ligation is implicated in active protein metabolism and subcellular trafficking and its impairment is involved in various neurologic diseases. In rat brain, we identified two novel Ub ligases, Momo and Sakura, carrying double zinc finger motif and RING finger domain. Momo expression is enriched in the brain gray matter and testis, and Sakura expression is more widely detected in the brain white matter as well as in many peripheral organs. Both proteins associate with the cell membranes of neuronal and/or glial cells. We examined their Ub ligase activity in vivo and in vitro using viral expression vectors carrying myc‐tagged Momo and Sakura. Overexpression of either Momo or Sakura in mixed cortical cultures increased total polyubiquitination levels. In vitro ubiquitination assay revealed that the combination of Momo and UbcH4 and H5c, or of Sakura and UbcH4, H5c and H6 is required for the reaction. Deletion mutagenesis suggested that the E3 Ub ligase activity of Momo and Sakura depended on their C‐terminal domains containing RING finger structure, while their N‐terminal domains influenced their membrane association. In agreement, Sakura associating with the membrane was specifically palmitoylated. Although the molecular targets of their Ub ligation remain to be identified, these findings imply a novel function of the palmitoylated E3 Ub ligase(s).