Isolation of mutations in Dictyostelium discoideum affecting α-mannosidase

We have isolated mutant strains of the cellular slime mold, Dictyostelium discoideum, which specifically lack α-mannosidase-1. This enzyme accumulates during the developmental phase of the life cycle. A minor isozyme, α-mannosidase-2, was recognized which accumulates only during culmination and makes up about 10 p. cent of the total activity in fruiting bodies. The minor isozyme has a pH response distinctly different from the major isozyme. Loss of the major isozyme, α-mannosidase-1, does not disrupt the normal sequence of biochemical differentiations.