Abstract
The biochemical properties of a chick pancreatic calcium binding protein (CaBP) and its response to vitamin D status and dietary calcium and phosphorus levels were studied and compared with the known vitamin D-dependent CaBPs present in the chick intestine and kidney. Pancreatic CaBP is homologous to the intestinal CaBP on the basis of immunological cross-reactivity, molecular size (28,200 Da), and charge properties (chromatographic mobility on DEAE-Sephadex in the presence of either EDTA or Ca 2+). Pancreatic levels of CaBP respond to changes in vitamin D status and dietary Ca and P level in a fashion similar to the intestinal CaBP. Thus, in the absence of dietary vitamin D, both pancreatic and intestinal CaBPs were essentially undetectable, while in the presence of dietary vitamin D, a low dietary P (0.05%) elevated the pancreatic and intestinal CaBP 1.5× and 1.6×, respectively, compared to the CaBP levels present with normal dietary Ca and P (1.0%, 1.0%). The tissue levels of pancreatic CaBP (6–10 ng/mg protein) are about 0.2% of the intestine (5000 ng/mg protein) and 1% of the kidney CaBP (700 ng/mg protein). However, when corrections are made for the CaBP distribution in the tissues and expressed as CaBP concentration per CaBP-containing cells, the pancreatic CaBP level was 30% of the intestine and 10% of the kidney. Collectively, these results suggest that the chick pancreatic vitamin D-dependent CaBP is a homologous protein to the intestinal CaBP, both with regards to its relative cellular concentration as well as in its response to changing dietary levels of Ca and P.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call