Figure 3.

Multiple determinants of Ca_vβ oligomerization. A) Domain structure of β₃ (485 aa) with regard to the fragments tested for binding to β₃. B) Co-IP of Flag-β₃ with indicated mVenus-labeled fragments of β₃ (lanes 1–9) and mVenus (lane C, control). C) Co-IP of Flag-labeled GKN and GKC with mVenus-labeled NN, NC, CN, and CC fragments or mVenus (lane C). D) Deletion of GK from the full-length β₃ subunit abolished its binding with other β₃ molecules. V5-His-β₃ and Flag-β₃ (left lanes) or Flag-β₃ΔGK (right lanes) were coexpressed in Cos7 cells (see lysates, right panel). Unlike Flag-β₃, Flag-β₃ΔGK was not bound to V5-His-β₃, as revealed by His pulldown (left panel). We used 0.5 μg of each plasmid for cotransfection.