PTHR1, a Parathyroid Hormone Receptor, mediates PTH-dependent regulation of mineral-ion homeostasis. It also mediates the paracrine action of PTHRP in endochondral bone formation. Mutations in this receptor are responsible for disorders of calcium and bone metabolism such as chondrodysplasia, hypercalcemia, and chronic renal failure. Three promoters, P1, P2, and P3, regulate the expression of PTHR. PTHR1 has been reported to be expressed in bone, breast, brain, colon, GI, kidney, liver, placenta, skin, umbilical cord, and uterus. ESTs have been isolated from B-cell/lung/testis, brain, breast, fetus, heart, heart/melanocyte/uterus, kidney, liver/spleen, lung, placenta, and testis libraries.