The RNA-binding protein PTBP1 is necessary for B cell selection in germinal centers.

Antibody affinity maturation occurs in germinal centers (GCs), where B cells cycle between the light zone (LZ) and the dark zone. In the LZ, GC B cells bearing immunoglobulins with the highest affinity for antigen receive positive selection signals from helper T cells, which promotes their rapid proliferation. Here we found that the RNA-binding protein PTBP1 was needed for the progression of GC B cells through late S phase of the cell cycle and for affinity maturation. PTBP1 was required for proper expression of the c-MYC-dependent gene program induced in GC B cells receiving T cell help and directly regulated the alternative splicing and abundance of transcripts that are increased during positive selection to promote proliferation

tRNA structural and functional changes induced by oxidative stress

Oxidatively damaged biomolecules impair cellular functions and contribute to the pathology of a variety of diseases. RNA is also attacked by reactive oxygen species, and oxidized RNA is increasingly recognized as an important contributor to neurodegenerative complications in humans. Recently, evidence has accumulated supporting the notion that tRNA is involved in cellular responses to various stress conditions. This review focuses on the intriguing consequences of oxidative modification of tRNA at the structural and functional level

Mechanisms of Falling Rock Formation at Steep Slope due to Temperature Perturbation

資源・素材学会平成24年度春季大会、2012年3月26日（月）～28日（水）、東京大学本郷キャンパス、東京

15N-Labelled proteins by cell-free protein synthesis. Strategies for high-throughput NMR studies of proteins and protein-ligand complexes

Abstract [15N]-heteronuclear single quantum coherence (HSQC) spectra provide a readily accessible fingerprint of [15N]-labelled proteins, where the backbone amide group of each nonproline amino acid residue contributes a single cross-peak. Cell-free protein synthesis offers a fast and economical route to enhance the information content of [15N]-HSQC spectra by amino acid type selective [15N]-labelling. The samples can be measured without chromatographic protein purification, dilution of isotopes by transaminase activities are suppressed, and a combinatorial isotope labelling scheme can be adopted that combines reduced spectral overlap with a minimum number of samples for the identification of all [15N]-HSQC cross-peaks by amino acid residue type. These techniques are particularly powerful for tracking [15N]-HSQC cross-peaks after titration with unlabelled ligand molecules or macromolecular binding partners. In particular, combinatorial isotope labelling can provide complete cross-peak identification by amino acid type in 24 h, including protein production and NMR measurement