Figure 1. RIM-Binding Protein Is Required for Homeostatic Synaptic Plasticity.

(A) Top: Schematic of the drbp locus indicating the approximate location of the drbp^STOP1 mutation. The 19 coding exons are represented by gray boxes ('1' denotes the first exon), and the red line refers the approximate location of the drbp^S2.01 deletion. Bottom: Schematic of RBP protein structure. Boxes denote the locations of the Src homology 3 domains (SH3), and the fibronectin type 3 (FN3) domains.

(B) Representative traces of EPSPs and mEPSPs for wild type in the absence and presence of PhTX (gray and black data; respectively), and drbp^STOP1 placed over the deficiency drbp^S2.01 in the absence and presence of PhTX (‘drbp’; light red, and dark red data; respectively; 1.5mM [Ca²⁺]_e).

(C) Average mEPSP amplitudes (left), EPSP amplitudes (middle), and quantal content (EPSP/mEPSP; right) of the indicated genotypes minus PhTX (light gray/red) and plus PhTX (black, dark red). w¹¹¹⁸ (−PhTX): n=8; w¹¹¹⁸ (+PhTX): n=7; drbp (−PhTX): n=16; drbp (+PhTX): n=17.

(D) Sample EPSCs of the indicated genotypes in the absence and presence of PhTX (‘−/+ PhTX’) at 3mM [Ca²⁺]_e (top row) and 15mM [Ca²⁺]_e (bottom row).

(E) Relationship between mean EPSC amplitude and extracellular Ca²⁺ concentration in wild type (control: light gray, n=4–7 per [Ca²⁺]_e; PhTX: dark gray, n=4–7 per [Ca²⁺]_e), and drbp (control: light red, n=8–12 per [Ca²⁺]_e; PhTX: dark red, n=6–12 per [Ca²⁺]_e). The wild-type data for the two lowest [Ca²⁺]_e were already published (Müller et al., 2012).