In this study, this protein was overexpressed in yeast cells grown on trehalose-containing medium to assess its impact on yeast vacuolar activity. ATH was confirmed to be located in both cell surface and vacuoles and the overexpression of ATH was observed to decrease vacuolar activity. Therefore, an assumption was suggested to explain this phenomenon as follows: when grown on containing trehalose medium, the ATH localization at cellular periplasm, but not the vacuole, is prioritized to utilize the extracellular trehalose for cell growth. The multivesicular body pathway (MVB pathway) via which ATH is transported into vacuoles is believed to be down-regulated to favor the accumulation of ATH at cell surface area. By extension, other vacuolar proteins travelling through MVB pathway to reach yeast vacuoles likely also suffer the down regulation. It can be concluded that acid trehalase may contribute down regulation of other vacuolar proteins through MVB pathway. This study suggests that it is a potential of acid trehalase (ATH) on impaired activity of yeast vacuolar. (C) 2016 Elsevier Inc. All rights reserved.