Nature's remedy to phosphate woes: calciprotein particles regulate systemic mineral metabolism.

Calciprotein particles, colloidal complexes of calcium phosphate and plasma protein fetuin-A, have emerged as mediators of multiple biological effects attributed to phosphate. A new study postulates that circulating calciprotein particles, not phosphate, regulate the production of the major bone-derived phosphatonin, fibroblast growth factor-23. The signaling events coupling calciprotein particles sensing in bone to fibroblast growth factor-23 secretion remain to be established.