Klotho beta protein (KLB)

Klotho beta (KLB) is a type I transmembrane protein that functions as an obligate co-receptor for the endocrine fibroblast growth factors FGF19 and FGF21. It primarily expressed in the liver and pancreas, and plays a crucial role in regulating metabolism, particularly bile acid synthesis and glucose uptake. KLB forms a complex with FGFRs to mediate downstream signaling, impacting various cellular processes. Mutations or dysregulation of KLB have been linked to hypogonadotropic hypogonadism and functional diarrhea.

KLB acts as an obligate co-receptor for specific endocrine fibroblast growth factors (FGFs) such as FGF19 and FGF21. It forms a ternary complex with FGFRs (fibroblast growth factor receptors) to mediate signaling, enhancing binding affinity between these FGFs and their respective receptors.