Synaptotagmin XVII (SytXVII), also known as Synaptotagmin-17 (SYT17) or Protein B/K, is a 474 amino acid peripheral membrane protein that belongs to the Synaptotagmin family and contains two C2 domains. While expressed abundantly in brain (frontal and temporal lobes, hippocampus, hypothalamus, amygdala, substantia nigra and pituitary), kidney and prostate, Synaptotagmin XVII is also expressed in fetal brain, kidney and lung.