Figure 3.
MTM1 mutations associated with severe myotubular myopathy dramatically decrease the phosphatase activity of myotubularin. Recombinant wild-type or mutant (P205L, R241L, S376N, G378R, Y397C) myotubularin fusion proteins were tested for their ability to dephosphorylate pNPP and PI(3)P substrates. Phosphatase assays were conducted at 30°C as described in Materials and Methods. Values are expressed as percent wild-type myotubularin activity (mean ± SEM).