Acta Medica Okayama 105 15 2008 Identification of a vesicular nucleotide transporter 5683 5686 EN Keisuke Sawada Noriko Echigo Narinobu Juge Takaaki Miyaji Masato Otsuka Hiroshi Omote Akitsugu Yamamoto Yoshinori Moriyama <p>ATP is a major chemical transmitter in purinergic signal transmission. Before secretion, ATP is stored in secretory vesicles found in purinergic cells. Although the presence of active transport mechanisms for ATP has been postulated for a long time, the proteins responsible for its vesicular accumulation remains unknown. The transporter encoded by the human and mouse SLC17A9 gene, a novel member of an anion transporter family, was predominantly expressed in the brain and adrenal gland. The mouse and bovine counterparts were associated with adrenal chromaffin granules. Proteoliposomes containing purified transporter actively took up ATP, ADP, and GTP by using membrane potential as the driving force. The uptake properties of the reconstituted transporter were similar to that of the ATP uptake by synaptic vesicles and chromaffin granules. Suppression of endogenous SLC17A9 expression in PC12 cells decreased exocytosis of ATP. These findings strongly suggest that SLC17A9 protein is a vesicular nucleotide transporter and should lead to the elucidation of the molecular mechanism of ATP secretion in purinergic signal transmission. </p> No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 102 50 2007 A human transporter protein that mediates the final excretion step for toxic organic cations 17923 17928 EN Masato Otsuka Takuya Matsumoto Riyo Morimoto Shigeo Arioka Hiroshi Omote Yoshinori Moriyama <p>In mammals, toxic electrolytes of endogenous and exogenous origin are excreted through the urine and bile. Before excretion, these compounds cross numerous cellular membranes in a transporter-mediated manner. However, the protein transporters involved in the final excretion step are poorly understood. Here, we show that MATE1, a human and mouse orthologue of the multidrug and toxin extrusion (MATE) family conferring multidrug resistance on bacteria, is primarily expressed in the kidney and liver, where it is localized to the luminal membranes of the urinary tubules and bile canaliculi. When expressed in HEK293 cells, MATE1 mediates H+-coupled electroneutral exchange of tetraethylammonium (TEA) and 1-methyl-4-phenylpyridinium (MPP). Its substrate specificity is similar to those of renal and hepatic H+-coupled organic cations (OCs) export. Thus, MATE1 appears to be the long searched for polyspecific OC exporter that directly transports toxic OCs into urine and bile.</p> No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 1996 アルコール摂取時に生ずるアセトアルデヒド,ジアセチル,アセトイン,2,3 -ブタンジオール等の生理化学的研究 EN Masato Otsuka No potential conflict of interest relevant to this article was reported.