STIM1 (G555) Antibody #4149

Ca²⁺ is a key second messenger in many intracellular signaling pathways. Ca²⁺ signals control many cellular functions ranging from short-term responses such as contraction and secretion to longer-term regulation of cell growth and proliferation (1,2). Stromal interaction molecules (STIMs) function as Ca²⁺ sensors that detect changes in Ca²⁺ content in intracellular Ca²⁺ stores (3). STIM1 is conserved, ubiquitously expressed, and functions as an endoplasmic reticulum (ER) Ca²⁺ sensor that migrates from the ER Ca²⁺ store to the plasma membrane where it activates calcium-release-activated calcium (CRAC) channels when the ER Ca²⁺ store is low (4). STIM1 is a potential tumor suppressor; defects in STIM1 may cause rhabdomyosarcoma and rhabdoid tumors (5). STIM1 can either homodimerize or form heterodimers with STIM2. STIM2 possesses a high sequence identity to STIM1 and can function as an inhibitor of STIM1-mediated plasma membrane store-operated Ca²⁺ entry (6). However, further investigation is required to elucidate the true physiological function of STIM2.