CD2 is a receptor expressed on T cells and when engaged, it promotes T cell activation. However the mechanisms and molecular partners of CD2 that mediate T cell activation remain unclear. Here we used AP-MS to determine the interactome of CD2 prior and upon its engagement. For this purpose, we used a knockin mouse expressing an endogenous One Step Tag (OST) version of the CD2 molecule. Affinity purification of the OST tagged protein was performed using Streptactin beads, from T cells left non-stimulated, or stimulated for 1min or 5min with anti-CD2 antibodies. Each AP-MS purification was associated with a corresponding control (purification from WT CD4+ T cells, cultured and stimulated in the same conditions). The number of replicate biological experiments was n=3 for all conditions.