Publications by authors named "Michio Koyama"

Channelrhodopsin (ChR) is a light-gated cation channel that responds to blue light. Since ChR can be readily expressed in specific neurons to precisely control their activities by light, it has become a powerful tool in neuroscience. Although the recently solved crystal structure of a chimeric ChR, C1C2, provided the structural basis for ChR, our understanding of the molecular mechanism of ChR still remains limited.

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Proton-dependent oligopeptide transporters (POTs) are major facilitator superfamily (MFS) proteins that mediate the uptake of peptides and peptide-like molecules, using the inwardly directed H(+) gradient across the membrane. The human POT family transporter peptide transporter 1 is present in the brush border membrane of the small intestine and is involved in the uptake of nutrient peptides and drug molecules such as β-lactam antibiotics. Although previous studies have provided insight into the overall structure of the POT family transporters, the question of how transport is coupled to both peptide and H(+) binding remains unanswered.

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Autotaxin (ATX) is a secreted lysophospholipase D that produces lysophosphatidic acid, a lipid mediator that activates G protein-coupled receptors to evoke various cellular responses. The nuclease-like domain of ATX and the Asn524-linked glycan are reportedly critical for the catalytic activity. Recently, the crystal structures of ATX were determined, but the means by which the nuclease-like domain and the N-glycosylation participate in the catalytic activity still remain undetermined.

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In the drug discovery process, it is important to know the properties of both drug candidates and their metabolites. Fast and precise prediction of metabolites is essential. However, it has been difficult to predict metabolites because of the complexity of the mechanism of cytochrome P450/3A4 (CYP 3A4), which is the main metabolite enzyme of drugs.

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