DETECTION OF CALBINDIN D-9K AND VITAMIN-D RECEPTOR EXPRESSION IN CHICK MUSCLE

1,25(OH)2D3 plays an important role in calcium homeostasis. It induces the expression of calcium binding proeins (CaBPs) or Calbindins in se veral tissues through a receptor-mediated genomic mechanism of action. The expression of the receptor itself is also modulated by the steroi d. In cultured chick myoblasts, 1,25(OH)2D3 stimulates the synthesis o f a minor 9 kDa CaBP whose partial characteristics ressemble those of mammalian Calbindin D-9K. Here we report the use of the polymerase cha in reaction (PCR) to confirm the presence of Calbindin D-9K gene in th e chick and its expression in muscle. PCR and hormone binding assays a re also used to study the expression of vitamin D receptor. They confi rm both muscle as a target for 1,25(OH)2D3 and the inducible synthesis of the vitamin D-receptor.