Centromeres are the chromosome loci for kinetochore assembly. They are attachment sites for microtubules during mitosis. CENP-A is a widely conserved protein, which specifically localizes at centromeres of every chromosomes, and is considered to be a fundamental epigenetic mark for centromeres. Since CENP-A shares high sequence similarity to histone H3, it has been supposed to be incorporated into the centromere-specific nucleosome, instead of histone H3. Recently, we determined the crystal structure of the human nucleosome containing CENP-A, and revealed its structural and functional properties. In this review, recent discoveries pertaining to the centromeric chromatin architecture containing CENP-A are described.
Channelrhodopsins (ChRs), which were first identified from Chlamydomonas genome, are light-gated ion channels. Although ChRs are now widely applied for optogenetics in many biomedical fields such as neuroscience, the mechanisms are mostly unknown how the light absorption can gate the ion channel to be open. In this review, the photocurrent kinetics of ChRs is discussed in relation to the photocycle models. The glutamic acid residues uniquely present in B helix appear to regulate the flux of permeable cations. One of them, E97 would lie in the outer pore and interact with a cation to facilitate the dehydration.
Living cells are viscoelastic materials, and thus the cell modulus changes with time and frequency. Recent progress in atomic force microscopy (AFM) combined with cell microarray substrates revealed that the number distribution of the complex shear modulus of cells exhibited a log-normal and became narrower with frequency, according to the power-law rheology model. Moreover, it was demonstrated that the force propagation between focal adhesions on the apical and basal cell surfaces could be directly measured using AFM with micropost substrates.