The R3 receptor-like protein tyrosine phosphatase subfamily inhibits insulin signalling by dephosphorylating the insulin receptor at specific sites
The autophosphorylation of specific tyrosine residues occurs in the cytoplasmic region of the insulin receptor (IR) upon insulin binding, and this in turn initiates signal transduction. The R3 subfamily (Ptprb, Ptprh, Ptprj and Ptpro) of receptor-like protein tyrosine phosphatases (RPTPs) is characterized by an extracellular region with 6–17 fibronectin type III-like repeats and a cytoplasmic region with a single phosphatase domain. We herein identified the IR as a substrate for R3 RPTPs by using the substrate-trapping mutants of R3 RPTPs. The co-expression of R3 RPTPs with the IR in HEK293T cells suppressed insulin-...
Source: Journal of Biochemistry - August 29, 2015 Category: Biochemistry Authors: Shintani, T., Higashi, S., Takeuchi, Y., Gaudio, E., Trapasso, F., Fusco, A., Noda, M. Tags: Regular Papers Source Type: research
Domain characterization of Bacillus subtilis GabR, a pyridoxal 5'-phosphate-dependent transcriptional regulator
Bacillus subtilis GabR is a transcriptional regulator consisting of a helix–turn–helix N-terminal DNA-binding domain, a pyridoxal 5'-phosphate (PLP)-binding C-terminal domain that has a structure homologous to aminotransferases, and a linker of 29 amino acid residues. In the presence of -aminobutyrate (GABA), GabR activates the transcription of gabT and gabD, which encode GABA aminotransferase and succinate semialdehyde dehydrogenase, respectively. We expressed N-terminal and C-terminal domain fragments (named N'-GabR and C'-GabR) in Escherichia coli cells, and obtained N'-GabR as a soluble monomer and C'-GabR ...
Source: Journal of Biochemistry - August 29, 2015 Category: Biochemistry Authors: Okuda, K., Ito, T., Goto, M., Takenaka, T., Hemmi, H., Yoshimura, T. Tags: Regular Papers Source Type: research
Diet-induced hypercholesterolemia imparts structure-function changes to erythrocyte chondroitin sulphate/dermatan sulphate
This study was carried out to determine whether diet-induced hypercholesterolemia had any effect on erythrocyte CS/DS and impacted cytoadherence to ECM components. Unlike in diabetes, diet-induced hypercholesterolemia did not show quantitative changes in erythrocyte CS/DS but showed difference in proportion of un-sulphated and 4-O-sulphated disaccharides. Erythrocytes from hypercholesterolemic rats showed increased adhesion to ECM components which was abrogated to various extents when subjected to chondroitinase ABC digestion. However, isolated CS/DS chains showed a different pattern of binding to ECM components indicating...
Source: Journal of Biochemistry - August 29, 2015 Category: Biochemistry Authors: Kiran, G., Srikanth, C. B., Salimath, P. V., Nandini, C. D. Tags: Regular Papers Source Type: research
Isolation and characterization of antigen-specific alpaca (Lama pacos) VHH antibodies by biopanning followed by high-throughput sequencing
The antigen-binding domain of camelid dimeric heavy chain antibodies, known as VHH or Nanobody, has much potential in pharmaceutical and industrial applications. To establish the isolation process of antigen-specific VHH, a VHH phage library was constructed with a diversity of 8.4 x 107 from cDNA of peripheral blood mononuclear cells of an alpaca (Lama pacos) immunized with a fragment of IZUMO1 (IZUMO1PFF) as a model antigen. By conventional biopanning, 13 antigen-specific VHHs were isolated. The amino acid sequences of these VHHs, designated as N-group VHHs, were very similar to each other (>93% identity). To find more...
Source: Journal of Biochemistry - August 29, 2015 Category: Biochemistry Authors: Miyazaki, N., Kiyose, N., Akazawa, Y., Takashima, M., Hagihara, Y., Inoue, N., Matsuda, T., Ogawa, R., Inoue, S., Ito, Y. Tags: Regular Papers Source Type: research
A new subset of deutan colour vision defect associated with an L/M visual pigment gene array of normal order and -71C substitution in the Japanese population
In 524 Japanese individuals with deutan colour vision defect, 76 had a normal-order pigment gene array, where the L gene is at the first position and the M gene(s) is located downstream. Of these 76 individuals, 69 had a –71A>C substitution in the M gene without any other mutation. Because the expression of L/M genes is up-regulated by thyroid hormone (T3) in human retinoblastoma WERI cells, we examined the effects of T3 on promoter activity; T3 increased the activity of the –71A promoter 2-fold, but it had no effect on the –71C promoter. Similarly, the –71C promoter was much less activated by T3...
Source: Journal of Biochemistry - August 29, 2015 Category: Biochemistry Authors: Ueyama, H., Muraki, S., Tanabe, S., Yamade, S., Ogita, H. Tags: Regular Papers Source Type: research
Fugu (Takifugu rubripes) serum GlcNAc-binding lectin is a kalliklectin but has different properties from those of a reported homologue
A 40-kDa lectin with N-acetyl-d-glucosamine-binding ability was purified from the sera of fugu (Takifugu rubripes) by affinity chromatography and subsequent gel filtration. N-terminal amino acid sequencing, in silico cloning using the fugu genome database and cDNA cloning demonstrated that this lectin is a homologue of kalliklectin, a novel lectin that was previously found in the flathead teleost Platycephalus indicus and has structural similarity to mammalian plasma kallikreins and coagulation factor XI. This is the second report of a kalliklectin, but the fugu kalliklectin differs in its sugar-binding spectra, intersubun...
Source: Journal of Biochemistry - August 29, 2015 Category: Biochemistry Authors: Tsutsui, S., Yamamura, N., Yoshida, T., Nakamura, O. Tags: Regular Papers Source Type: research
Low pH-driven folding of WW45-SARAH domain leads to stabilization of the WW45-Mst2 complex
In this study, refolding of the first Sav (known as WW45)-SARAH provided insight into the biochemical and biophysical properties, indicating that WW45-SARAH exhibits properties of a disordered protein, when the domain was refolded at a neutral pH. Interestingly, WW45-SARAH shows folded and rigid conformations relative to the decrease in pH. Further, diffracting crystals were obtained from protein refolded under acidic pH, suggesting that the refolded WW45 protein at low pH has a homogeneous and stable conformation. A comparative analysis of molecular properties found that the acidic-stable fold of WW45-SARAH enhances a het...
Source: Journal of Biochemistry - August 29, 2015 Category: Biochemistry Authors: Song, J., Hong, H. R., Yamashita, E., Park, I. Y., Lee, S. J. Tags: Regular Papers Source Type: research
Recent progress and perspective in JAK inhibitors for rheumatoid arthritis: from bench to bedside
Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by synovial inflammation and joint destruction. However, the combined use of synthetic disease-modifying anti-rheumatic drug (DMARD) such as methotrexate and a biological DMARD targeting tumour necrosis factor (TNF) has revolutionized treatment of RA. Clinical remission is a realistic target to treat and the maintenance of remission has produced significant improvements in structural and function outcomes. However, biological DMARDs are limited to intravenous or subcutaneous uses and orally available small but strong products have been developed. The ...
Source: Journal of Biochemistry - August 29, 2015 Category: Biochemistry Authors: Tanaka, Y. Tags: JB Review Source Type: research
Oxidation of translation factor EF-G transiently retards the translational elongation cycle in Escherichia coli
In Escherichia coli, elongation factor G (EF-G), a key protein in translational elongation, is particularly susceptible to oxidation. We demonstrated previously that EF-G is inactivated upon formation of an intramolecular disulphide bond. However, the details of the mechanism by which the oxidation of EF-G inhibits the function of EF-G on the ribosome remain to be elucidated. When we oxidized EF-G with hydrogen peroxide, neither the insertion of EF-G into the ribosome nor single-cycle translocation activity in vitro was affected. However, the GTPase activity and the dissociation of EF-G from the ribosome were suppressed wh...
Source: Journal of Biochemistry - July 28, 2015 Category: Biochemistry Authors: Nagano, T., Yutthanasirikul, R., Hihara, Y., Hisabori, T., Kanamori, T., Takeuchi, N., Ueda, T., Nishiyama, Y. Tags: Regular Papers Source Type: research
Close association of B2 bradykinin receptors with P2Y2 ATP receptors
Two G-protein-coupled receptors (GPCRs) that couple with Gαq/11, B2 bradykinin (BK) receptor (B2R) and ATP/UTP receptor P2Y2 (P2Y2R), are ubiquitously expressed and responsible for vascular tone, inflammation, and pain. We analysed the cellular signalling of P2Y2Rs in cells that express B2Rs. B2R desensitization induced by BK or B2R internalization-inducing glycans cross-desensitized the P2Y2R response to ATP/UTP. Fluorescence resonance energy transfer from P2Y2R-AcGFP to B2R-DsRed was detected in the cells and on the cell surfaces, showing the close association of these GPCRs. BK- and ATP-induced cross-internalizati...
Source: Journal of Biochemistry - July 28, 2015 Category: Biochemistry Authors: Yashima, S., Shimazaki, A., Mitoma, J., Nakagawa, T., Abe, M., Yamada, H., Higashi, H. Tags: Regular Papers Source Type: research
Rabin8 suppresses autophagosome formation independently of its guanine nucleotide-exchange activity towards Rab8
We examined the role of Rabin8 (a mammalian ortholog of Sec2p) with Rab8-GEF activity in autophagy in mammalian cells. Unexpectedly, depletion of Rabin8 promoted nutrient starvation-induced autophagosome formation, indicating that Rabin8 suppresses autophagosome formation. Depletion of Rab8 did not affect autophagosome formation, and expression of a Rabin8 GEF-domain mutant reverted the Rabin8 depletion-induced increase in autophagosomes, indicating that Rabin8 suppresses autophagosome formation independently of its Rab8-GEF activity. Nuclear Dbf2-related (NDR) kinases phosphorylate Rabin8 at Ser-272. The non-phosphorylata...
Source: Journal of Biochemistry - July 28, 2015 Category: Biochemistry Authors: Amagai, Y., Itoh, T., Fukuda, M., Mizuno, K. Tags: Regular Papers Source Type: research
Nrf2 up-regulates the induction of acidic sphingomyelinase by electrophiles
In this study, we clarified the involvement of NF-E2-related factor 2 (Nrf2) in the induction of ASMase mRNA by DEM. Promoter analysis using a series of deletion mutants of the human ASMase gene showed that ARE-like element1 located in a region between –200 and –160 bp upstream of the transcription start point is mainly a DEM-responsive element. Moreover, an electrophoretic mobility shift assay using ARE-like element1 revealed that Nrf2 is a candidate transcription factor that binds to ARE-like element1 in response to DEM. Finally, alteration of Nrf2 expression by overexpression and knockdown could regulate the...
Source: Journal of Biochemistry - July 28, 2015 Category: Biochemistry Authors: Kumagai, T., Kozakai, Y., Ishino, T., Yajima, Y., Nakagawa, Y., Imai, H. Tags: Regular Papers Source Type: research
Temperature-sensitive retinoid isomerase activity of RPE65 mutants associated with Leber Congenital Amaurosis
RPE65 is a membrane-associated retinoid isomerase involved in the visual cycle responsible for sustaining vision. Many mutations in the human RPE65 gene are associated with distinct forms of retinal degenerative diseases. The pathogenic mechanisms for most of these mutations remain poorly understood. Here, we show that three Leber congenital amaurosis -associated RPE65 mutants (R91W, Y249C and R515W) undergo rapid proteasomal degradation mediated by the 26 S proteasome non-ATPase regulatory subunit 13 (PSMD13) in cultured human retinal pigment epithelium (RPE) cells. These mutant proteins formed cytosolic inclusion bodies ...
Source: Journal of Biochemistry - July 28, 2015 Category: Biochemistry Authors: Li, S., Hu, J., Jin, R. J., Aiyar, A., Jacobson, S. G., Bok, D., Jin, M. Tags: Regular Papers Source Type: research
A cytoplasmic helix is required for pentamer formation of the Escherichia coli MscL mechanosensitive channel
Many membrane proteins such as ion channels are oligomers, but the determinants of the degree of oligomerization are not fully understood. Mechanosensitive channel with large conductance (MscL), which is ubiquitous in bacteria, is a homopentamer with two transmembrane helices and a cytoplasmic helix in each subunit. The carboxyl-terminal cytoplasmic helices assemble into a pentameric bundle that resembles cartilage oligomeric matrix protein. To address the role of cytoplasmic helices in the pentamer formation of Escherichia coli MscL, we generated MscL constructs with various deletions at the carboxyl terminus and translat...
Source: Journal of Biochemistry - July 28, 2015 Category: Biochemistry Authors: Ando, C., Liu, N., Yoshimura, K. Tags: Regular Papers Source Type: research
Albumin overload down-regulates integrin-{beta}1 through reactive oxygen species-endoplasmic reticulum stress pathway in podocytes
This study investigated whether urinary protein, particularly albumin, induced ER stress that consequently reduced integrin-β1 expression. All experiments were performed using primary cultured rat podocyte. Protein and mRNA expression were measured by western blotting and semiquantified reverse transcriptase polymerase chain reaction. Albumin uptake was found at 1 h after albumin addition. Albumin reduced precursor and mature forms of integrin-β1, but did not change mRNA levels of integrin-β1. Albumin induced reactive oxygen species (ROS) generation and ER stress. Antioxidant (N-acetylcysteine) suppressed al...
Source: Journal of Biochemistry - July 28, 2015 Category: Biochemistry Authors: Cheng, Y.-C., Chen, C.-A., Chang, J.-M., Chen, H.-C. Tags: Regular Papers Source Type: research
