Contactin-associated protein-like 2 (CNTNAP2) is a large transmembrane protein belonging to the neurexin superfamily, highly enriched in the nervous system, especially at axon initial segments and nodes of Ranvier. It plays critical roles in neuronal migration, axon myelination, synaptic formation, and ion channel clustering. CNTNAP2 is widely recognized as a key susceptibility gene linked to neurodevelopmental disorders such as autism spectrum disorder, intellectual disability, epilepsy, and language impairment. As a cell-adhesion and scaffolding molecule, it stabilizes membrane protein complexes and maintains neuronal excitability. CNTNAP2 physically associates with DPP6 to regulate potassium channel trafficking and neuronal membrane excitability. Briefly, DPP6 was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to CNTNAP2-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-DPP6 pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630nm immediately. Measured by its binding ability in a functional ELISA. When recombinant human CNTNAP2 is immobilized at 2 µg/mL(100 µL/well), the concentration of DPP6 that produces 50% optimal binding response is found to be approximately 0.195 µg/mL.