Signaling Threshold Regulating Transmembrane Adaptor 1 (SIT1) Protein

Background

Signaling Threshold-Regulating Transmembrane Adapter 1 (SIT1), also known as SIT, is an immunoregulatory protein primarily expressed in T cells. It acts as a transmembrane adaptor involved in modulating T-cell receptor (TCR) signaling by interacting with key intracellular signaling molecules such as Src family kinases and SH2 domain-containing phosphatases. SIT1 fine-tunes immune responses by negatively regulating TCR-mediated activation, thus maintaining immune tolerance and preventing overactivation that could lead to autoimmune diseases. Its dysregulation is associated with immune disorders and may affect T-cell maturation and peripheral immune homeostasis.