Fig. 12.

Assembly of CASK–Caskin 1 and CASK–Mint 1 complexes on the immobilized cytoplasmic domain of neurexin. Immobilized GST fusion protein of the wild-type cytoplasmic tail of neurexin 1 (GST–NxI) or of mutant cytoplasmic tail lacking the final 10 residues (NxIΔ10) was used for binding reactions with rat brain homogenates and eluted with 0.8 m K-acetate buffer (salt) followed by SDS sample buffer (SDS). Samples were analyzed by immunoblotting for CASK, Mint 1, Caskin 1, and GDI (as a negative control). Note the tight binding of CASK and Caskin 1 to the neurexin tail that requires the C-terminal residues of neurexin.Numbers at left indicate positions of molecular weight markers.