STRUCTURAL GENE FOR ALPHA-MANNOSIDASE-1 IN DICTYOSTELIUM-DISCOIDEUM

Abstract

Four independent mutations affecting .alpha.-mannosidase-1, a developmentally regulated activity in D. discoideum were isolated. Three of these result in a thermolabile .alpha.-mannosidase-1 activity. One mutation also affects the substrate affinity (Km) of the activity. On diploids these mutations show a gene dosage effect and are all alleles. The structural gene for .alpha.-mannosidase-1, as defined by these mutations, defines a new linkage group, linkage group VI. .alpha.-Mannosidase-1 is probably a homopolymer with subunits of 54,000 daltons. Two temperature-sensitive-for-growth mutations are mapped onto 2 previously defined linkage groups.