A novel centrosomal ring-finger protein, dorfin, mediates ubiquitin ligase activity.
We cloned a novel gene, Dorfin (double ring-finger protein), from human spinal cord. The Dorfin mRNA transcript was 4.4 kb and expressed ubiquitously in many organs as well as in the central nervous system, including the spinal cord. Dorfin encoded 838 amino acid protein Dorfin, which contains two RING-finger motifs and an IBR (in between RING-fingers) motif at its N-terminus. Dorfin is a short-lived protein. Treatment with MG132, a potent proteasome inhibitor, resulted in the accumulation of ubiquitinated Dorfin and Dorfin-associated cellular proteins in cultured cells. Dorfin bound specifically with human ubiquitin-conjugating enzymes UbcH7 and UbcH8 through the RING-finger/IBR domain. Partial deletion of the RING-finger/IBR domain eliminated these interaction and ubiquitination activities. These results strongly suggest that Dorfin is a new member of RING-finger type ubiquitin ligase. Dorfin is localized in the centrosome and probably functions in the microtubule organizing centers.
Department of Neurology, Nagoya University School of Medicine, 65 Tsurumai, Showa-ku, Nagoya, 466-8550, Japan.
J
J
Niwa
S
S
Ishigaki
M
M
Doyu
T
T
Suzuki
K
K
Tanaka
G
G
Sobue
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008025:Ligases / Q000378:metabolism*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D014452:Ubiquitins; C423571:RNF19A protein, human; D044767:Ubiquitin-Protein Ligases; D008025:Ligases