Four-helical cytokine, core <p>This entry represents a 4-helical bundle domain found predominantly in long- and short-chain cytokines, such as interleukins, interferons, growth hormones, and granulocyte colony stimulating factors. Cytokines play a crucial role in the development of an immune response by organising the recruitment and trafficking of immune cell populations throughout the body, usually through GPCR signalling [<cite idref="PUB00016345"/>]. Most cytokines have a predominantly alpha helical structure, and share a core domain consisting of a closed bundle of four helices in a left-handed twist, with two crossover connections [<cite idref="PUB00013238"/>].</p>