Figure 9. Model for RBP's Role in Homeostatic Plasticity and Vesicle Resupply.

Our data suggest that RBP (green), which is located in close proximity to voltage-gated Ca²⁺ channels (‘Ca Ch’, blue) (Liu et al., 2011), is necessary for both, the homeostatic enhancement of presynaptic Ca²⁺ influx (‘1. RBP’) and for the homeostatic increase in the number of release-ready vesicles (‘2. RBP’). Under baseline conditions, RBP is required for ‘tight coupling’ between vesicles and Ca²⁺ channels (note the increased distance between vesicle and Ca²⁺ channel in rbp), normal levels of presynaptic Ca²⁺ influx (decreased Ca²⁺ domain size in rbp) (Liu et al., 2011), and for the rapid resupply of ‘fast’ release-ready vesicles (green arrow).