Hohman T C, Bowers B
Eur J Cell Biol. 1986 Jan;39(2):475-80.
Lysosomal hydrolases are continually secreted by Acanthamoeba as a consequence of membrane cycling between the vacuolar compartment and the cell surface. In pinocytosing amoebae acid hydrolases can be separated into two groups on the basis of their secretion kinetics. We have previously shown that in Acanthamoeba acid hydrolases are almost exclusively restricted to a single compartment, digestive vacuoles, and that pH-dependent differential binding of hydrolases to vacuolar membrane can account for the different rates of hydrolase secretion from this compartment. In this report we show that the hydrolase secretion pattern changes and that all of the hydrolases are released with the same kinetics after phagocytosis of yeast or in growth media supplemented with ammonium acetate or chloroquine, but not after phagocytosis of polystyrene beads. The changes in the pattern of hydrolase secretion correlate with changes in vacuolar pH. The vacuolar pH of pinocytosing amoebae and amoebae saturated with beads is about 4.8. This value is increased to 6.8 by accumulation of weak bases and to about 6.1 when digestive vacuoles are saturated with yeast. These results indicate that vacuolar pH modulates hydrolase transport and secretion.
由于液泡区室与细胞表面之间的膜循环，溶酶体水解酶不断地由棘阿米巴分泌。在进行胞饮作用的阿米巴中，酸性水解酶可根据其分泌动力学分为两组。我们之前已经表明，在棘阿米巴中，酸性水解酶几乎完全局限于单个区室，即消化液泡，并且水解酶与液泡膜的pH依赖性差异结合可以解释该区域水解酶分泌的不同速率。在本报告中，我们表明，在吞噬酵母后或在补充有乙酸铵或氯喹的生长培养基中，水解酶的分泌模式会发生变化，并且所有水解酶都以相同的动力学释放，但在吞噬聚苯乙烯珠后则不会。水解酶分泌模式的变化与液泡pH值的变化相关。进行胞饮作用的阿米巴和充满珠子的阿米巴的液泡pH约为4.8。通过弱碱的积累，该值增加到6.8，当消化液泡充满酵母时，该值增加到约6.1。这些结果表明液泡pH调节水解酶的转运和分泌。
