Suppression inducing transmembrane adaptor 1, or Signaling threshold regulating transmembrane adaptor 1, is a human gene encoded by SIT1. It may also be known as: Signaling threshold-regulating transmembrane adapter 1; Suppression-inducing transmembrane adapter 1; gp30/40; SHP2-interacting transmembrane adapter protein; SHP2 interacting transmembrane adaptor; SIT; SIT-R. The encoded protein has an amino acid length of 196 and a mass of 21.1 kDa. Other isoforms may exist. Homologs of this gene exist in other organisms, including: Rat.