Skeletrophin is one of three ubiquitin ligases, the substrate of which is a cytoplasmic region of Notch ligands and positively regulates ligand-dependent Notch activation. The gene maps to human chromosome position 1p36.32–33, where tumor suppressor factors for neuroendocrine tumors are encoded. Although at least six alternative splicing forms have been found in the public database, the major human product, which is expressed in many tissues, is composed of 999 amino acids and is approximately 110 kDa. Skeletrophin is localized in the cytoplasm and is widely expressed in various adult tissues, with particularly strong expression in the skeletal muscle, heart, and brain tissue. There are also alternative splicing forms expressed specifically in the brain and forms expressed specifically in the developing brain.