indole-3-glycerol-phosphate synthase activity https://github.com/geneontology/go-ontology/issues/30193 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose-5-phosphate carboxy-lyase (cyclizing) MetaCyc:IGPSYN-RXN EC:4.1.1.48 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose-5-phosphate carboxy-lyase [cyclizing; 1-C-(3-indolyl)-glycerol-3-phosphate-forming] GO:0004425 molecular_function RHEA:23476 Catalysis of the reaction: 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate = 1-(indol-3-yl)glycerol 3-phosphate + CO2 + H2O. indoleglycerol phosphate synthase activity indoleglycerol phosphate synthetase activity indole-3-glycerophosphate synthase activity carboxy-lyase activity