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. 2017 Oct 20;39(2):112–122. doi: 10.1016/j.it.2017.10.001

Figure 1.

Figure 1

Paired Receptors Mediate a Balanced Form of Inhibition. (A) Schematic representation of a receptor pair. The shared ligand can bind either receptor, but the receptors themselves have opposite downstream signals, either activating or inhibitory. (B) Several mechanisms cause the inhibitory signal to be dominant over the activating signal when both paired receptors are expressed on the same cell. (B1). The inhibitory receptor (marked in red), has a higher affinity for the shared ligand than the activating receptor in all receptor pairs (for example, TIGIT versus DNAM1 8, 38). (B2) As a result of its higher affinity for ligand, the inhibitory receptor competes with its activating partner for ligand binding such that the inhibitory receptor physically interrupts the binding of the activating receptor to the ligand 8, 38. (B3) There is also evidence that inhibitory receptors can interfere with the homodimerization of their corresponding activating receptor, thereby preventing signalling through the activating receptor (e.g., TIGIT can interfere with the homodimerisation of DNAM1 [20]). Abbreviations: DNAM1, DNAX accessory molecule 1; TIGIT, T cell immunoreceptor with immunglobulin and ITIM domains.