Figure 9.

Multimerization of wild-type and C2A*-C2B* Syt1. A, Western blot with anti-GFP antibodies is shown to demonstrate Ca²⁺-independent and Ca²⁺-dependent binding of endogenous GFP-tagged Syt1, purified from adult head lysates, to GST-fused wild-type (C2A-C2B) or Ca²⁺-binding defective (C2A*-C2B*) Syt1. Fly head extracts are incubated with GST-fused Syt1 in the absence (EGTA, 2 mm) or presence of Ca²⁺ (1 or 10 mm). B, Binding of purified wild-type Syt1-His₆ to wild-type or Ca²⁺-binding defective GST-Syt1. GST-Syt1 (C2A-C2B and C2A*-C2B*) and interacting wild-type Syt1-His₆ products are indicated with arrows (top two bands) and a bracket (a single bottom band), respectively.