Klothoβ is a membrane-bound protein that belongs to the Klotho family of proteins, which also includes the soluble form αKlotho. In mice, Klothoβ is predominantly expressed in the kidney, brain, and reproductive organs, and plays a key role in regulating various physiological processes, including aging, mineral metabolism, and insulin signaling. Klothoβ functions as a co-receptor for fibroblast growth factor (FGF) receptors, enhancing the binding of FGF ligands to their receptors and potentiating downstream signaling cascades. Through its interaction with FGF receptors, Klothoβ modulates cell proliferation, differentiation, and survival, as well as metabolic homeostasis and tissue repair. Klothoβ is also involved in the regulation of phosphate and calcium metabolism, and has been implicated in the pathogenesis of age-related diseases and metabolic disorders.