Negatively regulates Golgi-to-plasma membrane trafficking by interacting with PI4KB and inhibiting its activity. Interacts with PI4KB. This binding competes with FREQ/NCS1 binding in a calcium-dependent manner. Brain-specific. Restricted to the CA3 region of the hippocampus, entorhinal cortex, the antero-dorsal and antero-ventral thalamus and the inferior and superior colliculus. The C-terminal transmembrane domain (TMD) is necessary and sufficient for membrane targeting. The calcium-binding affinity is not regulated by magnesium.