The yeast Saccharomyces cerevisiae is known as an available host for human G-protein-coupled receptor (GPCR) ligand screening. Although several types of yeast signal sequences (SS) attached with the GPCRs could improve their productivities and facilitate transportation of the GPCRs to the yeast plasma membrane, the effects of additional SS on ligand-specific signalling functions of GPCRs are not reported. Here, we demonstrated the controlling signalling properties by addition of SS using engineered yeast as a host. Prepro and pre regions of alpha-factor and amino-terminal sequence of Ste2 (Ste2N) were used as SS, and somatostatin (SST) receptor subtype-5 (SSTR5) was used as a model GPCR. We also constructed a yeast-based fluorescent assay system for monitoring the activation levels of SSTR5 signalling by a green fluorescent protein (GFP) reporter gene. The production levels and localisation patterns of the SS-attached SSTR5 were more significantly improved than those of wild-type SSTR5. In addition, we successfully controlled the pharmacological efficacy and potency by introducing SS. Among four types of SSTR5 receptors, Ste2N-SSTR5 responded at the lowest ligand concentration. This finding will be informative for constructing optimal yeast-based ligand screening systems to discriminate the cells on the basis of signalling levels.

We experimentally studied the optimization of the hot-C + -ion implantation process for forming nano-SiC (silicon carbide) regions in a (100) Si-oninsulator substrate at various hot-C + -ion implantation temperatures and C + ion doses to improve photoluminescence (PL) intensity for future Sibased photonic devices. We successfully optimized the process by hot-C + -ion implantation at a temperature of about 700 °C and a C + ion dose of approximately 4 ' 10 16 cm %2 to realize a high intensity of PL emitted from an approximately 1.5-nm-thick C atom segregation layer near the surface-oxide/Si interface. Moreover, atom probe tomography showed that implanted C atoms cluster in the Si layer and near the oxide/Si interface; thus, the C content locally condenses even in the C atom segregation layer, which leads to SiC formation. Corrector-spherical aberration transmission electron microscopy also showed that both 4H-SiC and 3C-SiC nanoareas near both the surface-oxide/Si and buried-oxide/Si interfaces partially grow into the oxide layer, and the observed PL photons are mainly emitted from the surface SiC nano areas.

The aim of this study is to examine the ability of the bile acid analogues obtained by chemical modification of ursodeoxycholic acid (UDCA) for TGR5 activation. Eleven UDCA analogues including 3-or 7-methylated UDCAs and amino acid conjugates were investigated as to their ability to activate TGR5 by means of the luciferase assay. It was noteworthy that 7a a-methylated UDCA, namely 3a a,7b b-dihydroxy-7a a-methyl-5b b-cholanoic acid, had a significantly high affinity for and ability to activate TGR5 as compared to UDCA. Additionally, FXR activation ability of 7a a-methylated UDCA was low relative to that of UDCA. However, other modification of UDCA, such as the introduction of methyl group at its C-3 position and oxidation or epimerization of hydroxyl group in the C-3 position, could not elicit such remarkable effect. The present findings would provide a useful strategy for the development of TGR5-selective agonist.

No abstract