Enzymatic activity of MTMR7. (A) Radiolabeled PtdIns substrates (100μM) were incubated with or without GST-MTMR7 (3.5 μg) at 37°C for 15 min, and the remaining substrate was analyzed by TLC. (B) The substrate specificity of MTMR7 with water-soluble inositol polyphosphates. GST-MTMR7 (89 ng) was incubated with 100 μM of each substrate at 37°C for 10 min. Released inorganic phosphate was determined by a dye-assay method (27). PtdIns(3,4)P2, PtdIns 3,4-bisphosphate; PtdIns(3,5)P2, PtdIns 3,5-bisphosphate; PtdIns(3,4,5)P3, PtdIns 3,4,5-trisphosphate; Ins(1,4)P2, inositol 1,4-bisphosphate; Ins(1,3,4)P3, inositol 1,3,4-trisphosphate; Ins(1,3,4,5)P4, inositol 1,3,4,5-tetrakisphosphate; Ins(1,3,4,6)P4, inositol 1,3,4,6-tetrakisphosphate; Ins(3,4,5,6)P4, inositol 3,4,5,6-tetrakisphosphate; Ins(1,3,4,5,6)P5, inositol 1,3,4,5,6-pentakisphosphate; InsP6, inositol 1,2,3,4,5,6-hexakisphosphate.