Rines/RNF180, a novel RING finger gene-encoded product, is a membrane-bound ubiquitin ligase.
We identified and characterized a novel RING finger gene, Rines/RNF180, which is well conserved among vertebrates. Putative Rines gene product (Rines) contains a RING finger domain, a basic coiled-coil domain, a novel conserved domain (DSPRC) and a C-terminal hydrophobic region that is predicted to be a transmembrane domain. N-terminally epitope tagged-Rines (Nt-Rines) was detected in the endoplasmic reticulum membrane/nuclear envelope in cultured mammalian cells. Nt-Rines was not extracted by high salt or alkaline buffers and was degraded in intact endoplasmic reticulum treated with proteinase K, indicating that Nt-Rines is an integral membrane protein with most of its N-terminal regions in the cytoplasm. Rines was expressed in brain, kidney, testis and uterus of adult mice, and in developing lens and brain, particularly in the ventricular layer of the cerebral cortex at embryonic stages. In cultured cells, Nt-Rines can bind another protein and promoted its degradation. The degradation was inhibited by proteasomal inhibitors. In addition, Nt-Rines itself was heavily ubiquitinated and degraded by proteasome. The involvement of Rines in the ubiquitin-proteasome pathway was further supported by its binding to the UbcH6 ubiquitin-conjugating enzyme and by its trans-ubiquitination enhancing activities. These results suggest that Rines is a membrane-bound E3 ubiquitin ligase.
Ogawa
Miyuki
M
Laboratory for Comparative Neurogenesis, RIKEN Brain Science Institute, Wako-shi, Saitama 351-0198, Japan.
Mizugishi
Kiyomi
K
Ishiguro
Akira
A
Koyabu
Yoshio
Y
Imai
Yuzuru
Y
Takahashi
Ryosuke
R
Mikoshiba
Katsuhiko
K
Aruga
Jun
J
D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D017931:DNA Primers / Q000235:genetics; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008297:Male; D008566:Membranes / Q000201:enzymology; D051379:Mice; D008813:Mice, Inbred ICR; D041681:NIH 3T3 Cells; D011247:Pregnancy; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D054829:RING Finger Domains; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014018:Tissue Distribution; D014162:Transfection; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D012333:RNA, Messenger; D011994:Recombinant Proteins; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex