Involved in normal synaptic function through regulation of Ca(2+) influx and neurotransmitter release in photoreceptor synaptic terminals and in auditory transmission. Modulator of CACNA1D and CACNA1F, suppressing the calcium-dependent inactivation and shifting the activation range to more hyperpolarized voltages. Interacts with CACNA1F and CACNA1D (via IQ domain) in a calcium independent manner. Interacts (via N-terminus) with UNC119. Found in rod spherules and cone pedicles of the presynapses from both types of photoreceptors. Expressed in retina and in the inner hair cells (IHC) of the cochlea. Phosphorylated. Phosphorylation levels change with the light conditions and regulate the activity, but has no effect on calcium binding.