Figure 1.

Elementary steps in TCR triggering. (A) The relative concentrations of active kinase to phosphatase ([Lck]/[CD45]) is expected to modulate the concentration of phosphorylated TCR ([pY TCR]). (C) The kinase-phosphatase ratio itself is expected to be related to the concentration of TCR-pMHC complexes ([TCR-pMHC]). (D) The concentration of pMHC ([pMHC]) determines the concentration of TCR-pMHC complexes. (B) These elementary relationship are proposed to underlie TCR triggering (the increase in TCR phosphorylation in response to pMHC binding). Dashed gray lines indicate alternate relationships between the variables. Note that all panels depict schematics and are not the result of experiments or mathematical modeling.