Acts as an adapter for the myotubularin-related phosphatases (PubMed:11504939, PubMed:12847286, PubMed:23818870). Regulates phosphatase MTM1 protein stability and possibly its intracellular location (PubMed:23818870). By stabilizing MTM1 protein levels, required for skeletal muscle maintenance but not for myogenesis (By similarity).