TRPV6

TRPV6 is a membrane is_associated_with::calcium channel which is particularly involved in the first step in calcium absorption in the is_associated_with::intestine.

Nomenclature
When first discovered it was named CAT1, or ECaC2. The name TRPV6 was confirmed in 2005.

TRPV6 is a member of the is_associated_with::transient receptor potential (TRP) family of membrane proteins. Unlike most TRP channels, TRPV6 is selective for Ca2+ ions, a property shared with its close homologue, is_associated_with::TRPV5, which is mainly expressed in the kidney and plays a role in renal Ca2+ reabsorption.

Expression
TRPV6 expression has been described in the intestine in several species, including humans. The protein is located in the apical brush-border membrane of the intestinal enterocyte where it regulates calcium entry into the cell. It is most abundant in the proximal small intestine (duodenum and jejunum), along with the other calcium transport proteins, is_associated_with::calbindin and the calcium-pumping ATPase, is_associated_with::PMCA1. The TRPV6 calcium transporter also found in the human placenta, pancreas and prostate gland and in some species in the kidney, where the related channel TRPV5 is strongly expressed.

Vitamin D
Expression of TRPV6 is is_associated_with::vitamin D dependent in mice and humans. Its expression was greatly reduced in animals that do not express the vitamin D receptor.

Vitamin D treatment of human colon cancer cells, Caco-2, increased expression of TRPV6 transcripts, and also stimulated the transport of calcium, probably through increased TRPV6 expression. In human duodenal explants, TRPV6 transcript expression was increased 3-fold after 6h incubation with the active form of vitamin D, 1,25-dihydroxycholecalciferol.