抄録
The cytoplasmic calcium ion concentration is lower than that of extracellular space or intracellular calcium storage such as endoplasmic reticulum (ER) or mitochondria. The calcium influx from the extracellular space or the calcium release from the intracellular storage result in the change of this balance and this change is quite important for variable cellular functions.The initial step of protein exocytosis is the vesicular transport of protein from the ER to the Golgi apparatus. How can cytoplasmic calcium concentration change influence on the protein transport between ER and the Golgi? Ionomycin is a well known reagent which can release calcium from intracellular storage or can enhance the calcium influx from the extracellular space. When the protein transport kinetics is compared between ionomycin plus or minus conditions, it has been revealed that the protein transport between ER and the Golgi was inhibited in the presence of ionomycin. When the transport kinetics was examined with thapsigargin, which can release the calcium from the ER, we could not observe any inhibitory effect. These results indicate that the calcium influx from the outside of the cell may inhibit the protein transport between ER and the Golgi. [Jpn J Physiol 54 Suppl:S88 (2004)]
