CART

CART, also known as cocaine and amphetaminerelated transcript, is a 10 kDa secreted polypeptide produced by neuronal cell types in a variety of locations. In human, the molecule is synthesized as a 116 amino acid (aa) precursor with a 27 aa signal sequence an 89 aa mature segment. There are six Cterminal cysteines that form three intrachain disulfide bonds, and the potential exists for both sulfation and phosphorylation in the N terminal region. There are numerous monobasic and dibasic sites for enzyme cleavage, and multiple, presumably proteolyticallygenerated short forms are known to exist. These include a 5K, 48 aa peptide (CART 42- 89), and a 4.3K, 40 aa peptide (CART 49-89). Human CART is 98% aa identical to both mouse and rat CART (189). Although CART suppresses feeding and increases pain tolerance, there would appear to be differences between the various forms of CART on other functions. In addition, anatomical location is associated with differing lengths of CART. For example, 89 aa and 79 aa forms are found in the adrenal, while 48 aa and 44 aa forms are found in the hypothalamus.