MULTIPLE FORMS OF β -GALACTOSIDASE AND THE CHANGES IN ITS PATTERN DURING DEVELOPMENT OF DICTYOSTELIUM DISCOIDEUM

Four forms of β-galactosidase (EC 3.2.1.23) were separated from cell extracts of Dictyostelium discoideum by polyacrylamide gel electrophoresis. Changes in the pattern of multiple forms of this enzyme during differentiation and dedifferentiation were studied. The band closest to the anode (Band 1) existed throughout development, but the other three bands appeared and disappeared at certain stages. One of those bands was specific for the vegetative stage (Band 3), and another for the morphogenetic stages (Band 2). The last one predominantly appeared during dedifferentiation of disaggregated slug cells (Band 4), although it was slightly detected during culmination. During the process of dedifferentiation, the increase in activity of Band 4 coincided with the decrease in Band 2. After the completion of dedifferentiation, Band 4 also disappeared, only Band 1 remaining. These multiple forms were not only electrophoretically separable but different in their sensitivities to various inhibitors. All forms of the enzyme were localized in subcellular particles, probably in lysosomes and phagosomes, and the relative activities in these two fractions varied during development.