cDNA cloning of rat proteasome subunit RC1, a homologue of RING10 located in the human MHC class II region

AbstractThe nucleotide sequence of a cDNA that encodes a new subunit, named RC1, of rat proteasomes (multicatalytic proteinase complexes) has been determined. The polypeptide predicted from the open reading frame consisted of 208 amino acid residues with a calculated molecular mass of 23,130, which is consistent with the size obtained by electrophoretic analysis of purified RC1. The partial amino acid sequences of several fragments of RC1, obtained by protein chemical analyses, were found to be in excellent accordance with those deduced from the cDNA sequence. Surprisingly, the overall structure of RC1 was found to be almost identical to that of recently isolated RING10, whose gene is located in the class II region of the human MHC gene cluster. This finding suggests that RC1 is a homologue of human RING10, supporting the proposal that proteasomes are involved in the antigen processing pathway

Magnetic field effect on the chiral magnetism of noncentrosymmetric UPtGe: experiment and theory

The effect of differently oriented magnetic field on chiral incommensurate helimagnet UPtGe is studied both experimentally and theoretically. The magnetization measurements up to the field above the saturation have revealed an isotropic magnetic response below 20 T and a remarkable nonmonotonic anisotropy in high fields. Moreover, the two principally different phase transitions from the noncollinear incommensurate to the field-induced ferromagnetic state have been observed. These properties are successfully explained by density-functional theory calculations taking into account the noncollinearity of the magnetic structures, arbitrary directed magnetic field, and relativistic effects. We also estimate the strength of different competing magnetic interactions and discuss possible scenarios of the field-induced phase transformations.Comment: 7 pages, 6 figures, 1 tabl

cDNA cloning and sequencing of component C5 of proteasomes from rat hepatoma cells

AbstractProteasomes are multicatalytic proteinase complexes consisting of a set of non-identical polypeptide subunits. A cDNA for component C5 of rat proteasomes was isolated by screening a Reuber H4TG hepatoma cell cDNA library using synthetic oligodeoxynucleotide probes corresponding to partial amino acid sequences of the protein. The polypeptide deduced from the open reading frame consisted of 240 amino acid residues with a calculated molecular weight of 26479. Computer analysis revealed little similarity of C5 to other proteins reported so far. The primary structure of C5 showed partial sequence homology to that of another component C3, but no regions of homology with the sequence of component C2. Thus C5 is concluded to be a new type of subunit of the proteasome complex

OTUD1 deubiquitinase regulates NF-κB- and KEAP1-mediated inflammatory responses and reactive oxygen species-associated cell death pathways

Deubiquitinating enzymes (DUBs) regulate numerous cellular functions by removing ubiquitin modifications. We examined the effects of 88 human DUBs on linear ubiquitin chain assembly complex (LUBAC)-induced NF-κB activation, and identified OTUD1 as a potent suppressor. OTUD1 regulates the canonical NF-κB pathway by hydrolyzing K63-linked ubiquitin chains from NF-κB signaling factors, including LUBAC. OTUD1 negatively regulates the canonical NF-κB activation, apoptosis, and necroptosis, whereas OTUD1 upregulates the interferon (IFN) antiviral pathway. Mass spectrometric analysis showed that OTUD1 binds KEAP1, and the N-terminal intrinsically disordered region of OTUD1, which contains an ETGE motif, is indispensable for the KEAP1-binding. Indeed, OTUD1 is involved in the KEAP1-mediated antioxidant response and reactive oxygen species (ROS)-induced cell death, oxeiptosis. In Otud1−/−-mice, inflammation, oxidative damage, and cell death were enhanced in inflammatory bowel disease, acute hepatitis, and sepsis models. Thus, OTUD1 is a crucial regulator for the inflammatory, innate immune, and oxidative stress responses and ROS-associated cell death pathways

125Te-NMR Study on a Single Crystal of Heavy Fermion Superconductor UTe2

We report 125Te-NMR studies on a newly discovered heavy fermion superconductor UTe2. Using a single crystal, we have measured the 125Te-NMR Knight shift K and spin-lattice relaxation rate 1/T1 for fields along the three orthorhombic crystal axes. The data confirm a moderate Ising anisotropy for both the static (K) and dynamical susceptibilities (1/T1) in the paramagnetic state above about 20 K. Around 20 K, however, we have observed a sudden loss of NMR spin-echo signal due to sudden enhancement of the NMR spin-spin relaxation rate 1/T2, when the field is applied along the easy axis of magnetization (=a axis). This behavior suggests the development of longitudinal magnetic fluctuations along the a axis at very low frequencies below 20 K.Comment: 5 pages, 7 figures, accepted for publication in J. Phys. Soc. Jp