A 16-aa peptide sequence, within the N-terminal Ca-binding domain of mouse D9K. Calcium (Ca+2 or Ca) is the most abundant cation and it is required for many physiological activities such as bone formation and it acts as a second messenger in signal transduction. However only 1% of Ca is present in ionic form in biological fluids. Ca concentration is regulated by calcitropic hormones that act on bone, kidney, and intestine. Extracellular Ca+-levels are sensed and regulated by Calcium Sensing receptor (CASR). When Ca levels are limiting then it must be taken up by active, transcellular pathways comprising (1) Ca++ entry across apical membrane, (2) cytosolic transport of Ca++ across the cell form apical to basolateral membrane facilitated by a family of low mol wt Calcium binding proteins (CABPs) that include vitamin D3-dependent Ca++ binding proteins (calbindin-D9k, Calbindin-28k, Calretinin, Parvalbumin, S100, calmodulin) and finally (3) an active extrusion of Ca++ through basolateral membrane mediated by Ca++-ATPase and Na+-Ca++ exchangers (NCX). Ca++ absorption in intestine and its reabsorption in kidney are carried out by Ca++ Transport (CaT) proteins, CaT-1, CaT-2 or Epithelial Ca Channel (ECAC1/ECAC2/CaT-Like (CaT-L) proteins. Calbindins are Ca-binding proteins belonging to the troponin C superfamily. There are two types of CaBPs: the trigger- and the buffer-CaBPs. The conformation of trigger type CaBPs changes upon Ca2+ binding and exposes regions on protein that interact with target molecules, thus altering their activity. The buffer-type CABP are thought to control the intracellular calcium concentration. CABP9K (CALB3 or CABP1, mouse, rat, and human 79 aa, chromosome Xp, ~9kD) is a cytosolic Ca-binding protein initially found in rat pancreas. It is also expressed in intestine, placenta, uterus and kidney. Its expression is controlled by vitamin D and sex hormone in a tissue specific manner. In keeping with its role in Ca-transport, its expression is highest in duodenal villus enterocytes. It is further shown that CABP9K is only expressed in differentiated enterocytes. CABP9K gene also contains Cdx2-homeoprotein binding sites, and that Cdx2 may play a crucial role in CABP9K transcription.
Purity:
Highly purified
Form:
Supplied as a liquid in PBS, pH 7.2
* VAT and and shipping costs not included. Errors and price changes excepted
