Fig. 2

Illustration (combined from [27, 28]) of a receptor-ligand binding kinetics, which includes receptor protein coupling, internalization, and recycling, whose components can be interpreted as nested arrangements of objects within objects that interact at intersection points, can be approximated to spherical particles of various sizes, move in continuous space and undergo processes of creation, degradation, internalization, externalization, fusion, and fission. a Biological view, b Hollow spheres view