The CRAC Channel Activator STIM1 Binds and Inhibits L-Type Voltage-Gated Calcium Channels

Voltage-and store-operated calcium (Ca2+) channels are the major routes of Ca2+ entry in mammalian cells, but little is known about how cells coordinate the activity of these channels to generate coherent calcium signals. We found that STIM1 (stromal interaction molecule 1), the main activator of store-operated Ca2+ channels, directly suppresses depolarization-induced opening of the voltage-gated Ca2+ channel Ca(V)1.2. STIM1 binds to the C terminus of Ca(V)1.2 through its Ca2+ release-activated Ca2+ activation domain, acutely inhibits gating, and causes long-term internalization of the channel from the membrane. This establishes a previously unknown function for STIM1 and provides a molecular mechanism to explain the reciprocal regulation of these two channels in cells.