CASK Interacting Protein 1 (CASKIN1)

Caskin1, like Mint1, is stably bound to CASK in the brain. Affinity chromatography experiments determined that Caskin1 coassembles with CASK on the immobilized cytoplasmic tail of neurexin-1, suggesting that CASK and Caskin1 coat the cytoplasmic tails of neurexins and other cell surface proteins. Detailed mapping studies revealed that Caskin1 and Mint1 bind to the same site on the N-terminal CaM kinase domain of CASK and compete with each other for CASK binding. GST-pull-down experiments indicated that CASK forms a tripartite complex with Caskin1 and Velis similar to the CASK-Mint1-Veli complex. The Caskin1 sequence that binds to CASK is poorly conserved between Caskins 1 and 2 and GST-Caskin2 fusion experiments showed that Caskin2 does not bind to CASK.