Abstract
As one of the cellular slime mould mutants produced with restriction enzymes mediated integration (REMI), we isolated a strain that carries an insertion mutation in LmpB gene. LmpB is a lysosomal protein and suggested to be involved in the endosome maturation. Although some regulatory components associated with endosomes are commonly found in the contractile vacuoles, LmpB has not been suggested to be involved in the process of the osmotic regulation. However, when LmpB mutant cells were placed under osmotic stress, they developed morphologically aberrant large vacuoles in the cytoplasm and the viability of the cells was significantly reduced. The result implies that LmpB is not only involved in the endosome maturation, but also involved in the function of contractile vacuoles.
