PCSK1N is a 260 amino acid protein that is both secreted and localized to the trans-Golgi network. Expressed in pancreas and brain, PCSK1N is thought to play a role in the control of the neuroendocrine secretory pathway and may also be involved in PCSK1 inhibition. The gene encoding PCSK1N maps to human chromosome X, which contains nearly 153 million base pairs and houses over 1,000 genes. In conjunction with chromosome Y, chromosome X is responsible for sex determination, as an X and a Y chromosome lead to normal male development, while two copies of an X chromosome lead to normal female development. There are a number of conditions related to an abnormal number and combination of sex chromosomes, some of which include Turner's syndrome, color blindness, hemophilia and Duchenne muscular dystrophy.