Intestinal Membrane Calcium Binding Protein, also known as Calbindin-D9k, is a protein that plays a crucial role in calcium absorption and transport within the intestine. It belongs to the family of S-100 proteins and is primarily found in the brush border membrane of the intestinal cells.
The main function of Intestinal Membrane Calcium Binding Protein is to bind with calcium ions, facilitating their movement across the intestinal epithelial cells. By doing so, it increases the efficiency of calcium absorption from the diet into the bloodstream. This protein is especially important in the duodenum and proximal jejunum, regions of the small intestine where calcium absorption is most prominent.
Calbindin-D9k is known for its high affinity for calcium, and it acts as a buffer in the enterocytes, ensuring that calcium concentration within the cells remains balanced. This protein also helps in maintaining calcium homeostasis by sequestering excess calcium and preventing its toxicity. Additionally, it assists in the regulation of vitamin D-dependent calcium uptake by facilitating the translocation of the calcium channel protein, TRPV6, to the apical membrane of the intestinal cells.
Deficiencies in Intestinal Membrane Calcium Binding Protein can lead to impaired calcium absorption, resulting in conditions like osteoporosis, rickets, and hypocalcemia. Research has shown that factors such as vitamin D levels, hormonal regulation, and dietary calcium intake can impact the expression and activity of this protein.
In summary, Intestinal Membrane Calcium Binding Protein is a vital component of the intestinal calcium absorption machinery, ensuring efficient transport of calcium across the intestinal epithelium and contributing to overall calcium homeostasis in the body.
