This family consists of several cocaine and amphetamine regulated transcript type I protein (CART) sequences. Cocaine and amphetamine regulated transcript (CART) peptide has been shown to be an anorectic peptide that inhibits both normal and starvation-induced feeding and completely blocks the feeding response induced by neuropeptide Y and regulated by leptin in the hypothalamus. The C-terminal part containing the three disulfide bridges is the biologically active part of the molecule affecting food intake. The solution structure of the active part of CART has a fold equivalent to other functionally distinct small proteins. CART consists mainly of turns and loops spanned by a compact framework composed by a few small stretches of antiparallel beta-sheet common to cystine knots [1].

1: Solution structure of the satiety factor, CART, reveals new functionality of a well-known fold. Ludvigsen S, Thim L, Blom AM, Wulff BS; Biochemistry 2001;40:9082-9088. PMID:11478874