Abstract
The specific calcium-binding factor was fractionated from heat-treated rat intestinal mucosa supernatants with use of 45Ca-equilibrated Sephadex G-25.
Calcium-binding fraction was calcium specific, and consisted of two components. The first component was increased by vitamin D3 administration, suppressed with actinomycin D pretreatment, and decreased by trypsin digestion. On the other hand, the second component was not influenced by vitamin D3, but increased by trypsin digestion.
From these results, this factor would be protein. The second component might be a smaller fragment of the first component. Vitamin D3 would stimulate directly or indirectly the synthesis of specific calcium-binding protein.
