The CAPS2 gene encodes a protein called Calcyphosine 2.  The protein contains two EF-hand motifs required for calcium ion binding.  While CAPS2 is yet to be further characterized, recent studies have speculated a key role for the protein in neurotransmitter release.  It has been found that both CAPS1 and CAPS2 are essential components of the synaptic vesicle priming machinery, required for controlling the strength and plasticity of synaptic transmission between neurons.  Those neurons that are deficient in CAPS proteins have been shown to contain no or very few fusion competent synaptic vesicles, resulting in the selective impairment of fast phasic transmitter release.

The CAPS2 gene is located on the long arm of chromosome 12.  It spans a length of 133.8 kb of DNA and its coding sequence is spread across 24 exons.  The protein product encoded by the gene has a molecular mass of 63.8 kDa and consists of 557 amino acids.  Several different isoforms of the CAPS2 protein exist due to alternative splicing.  While the gene is widely expressed in the human body, highest expression is seen in the brain, lung, placenta, colon and testes.