Myotubularin related protein 7, a novel STIM1 binding protein

Stromal interaction molecule 1 (STIM1) is a Ca²⁺ sensor in the endoplasmic reticulum (ER) membrane. The protein plays a crucial role in store-operated Ca²⁺ entry (SOCE) by transducing ER Ca²⁺ depletion signals to Ca²⁺ release-activated Ca²⁺ channel protein 1 (ORAI1) at the plasma membrane. Myotubularin related protein 7 (MTMR7) is a lipid phosphatase that dephosphorylates phosphoinositides. Using yeast two-hybrid analysis, immunoprecipitation and fluorescence microscopy, we discovered that MTMR7 interacts with STIM1 at the ER. These observations identified MTMR7 as a novel STIM1-binding protein that bridges myotubularins and phosphoinositide signaling with SOCE. Our research revealed a novel link between Ca²⁺ signaling and phosphoinositide biology, positioning MTMR7 as a potential marker or drug target for SOCE related human pathophysiology.