Figure 3.
The interaction between Boc and the WRC occurs in live cells and is direct
(A–D) The NanoBiT structural complementation reporter system was used to detect interaction between Boc and CYFIP2 in live cells. Boc was fused to the Large BiT (LgBiT) subunit (Boc-LgBiT), and CYFIP2 was fused to the Small BiT (SmBiT) subunit either N-terminally (CYFIP2-SmBiT) or C-terminally (SmBiT-CYFIP2) and expressed in HEK293 or COS7 cells. When the two proteins interact, a luminescent signal is generated in the presence of substrate.
(A) Expression of Boc-LgBiT and CYFIP2-SmBit alone or (B) expression of Boc-LgBiT and SmBit-CYFIP2 alone does not generate a luminescent signal. (Left) When Boc-LgBiT is expressed with CYFIP2-SmBiT (A) or SmBit-CYFIP2 (B), they interact to generate a luminescent signal. (Right) Boc-LgBiT also interacts with CYFIP2-SmBiT (A) or SmBit-CYFIP2 (B) in the presence of co-expressed WRC components NCKAP1-Flag, WAVE1-Emerald, ABI1-EGFP, and BRK1-Myc-Flag (“+WRC”). Data are represented as mean ± SEM; error bars representing the SEM are too small to be visible. (Left) Repeated measures one-way ANOVA with Dunnett’s multiple comparison test, (right) paired t test. n = 2–6 independent experiments. ∗∗p < 0.01, ∗∗∗∗p < 0.0001.
(C) Boc lacking an intracellular domain (ICD), BocΔICD-LgBiT, has a significantly lower interaction with CYFIP2-SmBiT and (D) SmBiT-CYFIP2 compared to full-length Boc-LgBiT in the presence of the WRC components NCKAP1-Flag, WAVE1-Emerald, ABI1-EGFP, and BRK1-Myc-Flag. Data are represented as mean ± SEM. Paired t test, n = 3–5 independent experiments. ∗∗p < 0.01, ∗∗∗∗p < 0.0001.
(E) Schematic of GST-Boc ICD constructs.
(F) Coomassie-blue-stained SDS-PAGE gel showing MBP pull-down between purified (MBP)2-tagged HSPC300 or WRC and the indicated purified GST-Boc ICD proteins. Only GST-Boc ICD FL and GST-Boc ICD NT are pulled down by (MBP)2-WRC.