The protein utilizes C2 domains to bridge synaptic vesicles to the plasma membrane (plasma membrane being the "target membrane").

Structure and function of otoferlin, a synaptic protein of ... - PMC

Binding Sites: High-resolution structures revealed that multiple Ca 2+raised to the 2 plus power

Otoferlin engages the target membrane specifically through a large interface involving the N-terminal C2B and C-terminal C2F-C2G domains . Ca 2+raised to the 2 plus power