Neuronal calcium sensor, regulator of G protein-coupled receptor phosphorylation in a calcium dependent manner. Directly regulates GRK1 (RHOK), but not GRK2 to GRK5. Can substitute for calmodulin. Stimulates PI4KB kinase activity. Involved in long-term synaptic plasticity through its interaction with PICK1. May also play a role in neuron differentiation through inhibition of the activity of N-type voltage-gated calcium channel. Monomer (PubMed:25979333). Interacts with KCND2 (By similarity). Interacts in a calcium-independent manner with PI4KB, but only if myristoylated (PubMed:11526106). This binding competes with CALN2/CABP7 binding to PI4KB (PubMed:11526106). Interacts in a calcium-dependent manner with PICK1 (via AH domain) (PubMed:19109914). Interacts with ARF1, ARF3, ARF5 and ARF6 (By similarity). Interacts with IL1RAPL1 (By similarity). Associated with Golgi stacks. Post-synaptic densities of dendrites, and in the pre-synaptic nerve terminal at neuromuscular junctions. Binds 3 calcium ions via the second, third and fourth EF-hand. EF-2 and EF-3 bind both magnesium and calcium, while EF-4 binds only calcium. At the resting state, magnesium is bound to EF-2 and EF-3 and upon activation, both sites bind calcium simultaneously while EF-4 is the last one to be occupied. Fourfold reduction in calcium affinity for NCS1/FREQ in the presence of magnesium. Belongs to the recoverin family.