STING ER exit protein 1 (STEEP1)

STING ER exit protein 1 (STEEP1) is encoded by the CXorf56 gene and functions as a critical scaffold and regulator of STING1 trafficking from the endoplasmic reticulum to the Golgi apparatus, an essential step in cytosolic DNA-induced innate immune signaling. STEEP1 interacts with STING, promoting the recruitment of the class III PI3 kinase VPS34, resulting in localized phosphatidylinositol-3-phosphate (PI3P) production and membrane curvature at the ER. These events are necessary for the assembly of COPII vesicle machinery, enabling STING’s exit from the ER upon activation by cyclic dinucleotides (e.g., cGAMP). STEEP1 is essential for proper induction of type I interferons and proinflammatory cytokines (including IFN-β and IL-6) upon activation of STING by cytosolic DNA sensing. Loss-of-function studies show that absence of STEEP1 prevents STING ER exit, abolishing downstream signaling including autophagy and immune activation. Therefore, STEEP1 serves as a critical checkpoint in immune defense against infection and in the pathogenesis of certain inflammatory diseases. There are currently no drugs that specifically target STEEP1, nor is it described as a primary therapeutic target (such as a receptor or enzyme); its role is as a facilitator and regulator in the STING pathway.

Other names

CXorf56STEEPFLJ22965MRX107XLID107UPF0428 protein CXorf56