Myonectin (CTRP15) is a myokine, described in 2012 by Seldin, et al. It is a novel nutrient-responsive myokine secreted by skeletal muscle to regulate whole-body fatty acid metabolism. Myonectin is a member of the C1q/TNF-related protein (CTRP) family. This important, biologically active molecule is released into circulation by muscular contraction, and is roughly equivalent to insulin in its potency. It was shown to be identical to erythroferrone, a hormone produced in erythroblasts that is involved in iron metabolism.