Table 1. Summary of the fundamental kinetic constants introduced in Eq. 1 and Fig. 2.

Step	Dimension	Parameter†	Units	Description	Refs
Diffusion	3D		M−1 s−1	On-rate constant	16
Diffusion	3D		s−1	Off-rate constant	16
Diffusion	3D		M−1	Affinity	16
Rotation	3D		s−1	On-rate constant	15,21
Rotation	3D		s−1	Off-rate constant	15,21
Rotation	3D		—	Affinity	15,21
Diffusion	2D		s−1	On-rate constant	16
Diffusion	2D		s−1	Off-rate constant	16
Diffusion	2D			Affinity	16
Rotation	2D		s−1	On-rate constant	15,21
Rotation	2D		s−1	Off-rate constant	15,21
Rotation	2D		—	Affinity	15,21
Binding	—	k+	s−1	On-rate constant	15,21
Binding	—	k−	s−1	Off-rate constant	15,21
Binding	—	KA = k+/k−	—	Affinity	15,21

Note that the fundamental binding constants (k⁺, k⁻) and the corresponding binding affinity constant (K_A) are independent of the dimensionality of the experiment.

^†N_A, Avogradro constant. A_c, effective cell surface area, defined as A_c = πa², where a ≡ TCR encounter radius.