page_title: TRPV6
section_title: Ca2+ absorption in intestine
hierarchical_section_title: TRPV6 / Physiological functions / Ca2+ absorption in intestine
caption_attribution_description: English: Figure 4. Role of TRPV6 in intestinal calcium absorption. TRPV6 mediates Ca2+ entry across the plasma membrane as the first step in the transcellular pathway of Ca2+ transport. This is considered the rate-limiting step in Ca2+ absorption by the enterocytes. The transcellular pathway enables the transport of Ca2+ against a [Ca2+] gradient to ensure Ca2+ absorption when the luminal [Ca2+] is lower than that in the blood side; The Ca2+ binding protein calbindin-D9k and plasma membrane Ca2+ ATPase (PMCA) are known components in these transcellular pathways.
context_page_description: TRPV6 is a membrane calcium channel protein which is particularly involved in the first step in Ca²⁺absorption in the intestine.
context_section_description: Two routes of Ca²⁺ absorption are recognized: paracellular transport and transcellular transport (see Figure 4).  A high-Ca²⁺-diet favors paracellular transport of the ion across the length of the intestine allowing them to pass between the intercellular tight junctions that connect epithelial cells. In contrast under conditions when [Ca²⁺] in the lumen of the intestine is lower in comparison to its concentration in the plasma (e.g. during low dietary Ca²⁺), the transcellular pathway is required for adequate Ca²⁺ absorption. Three important steps in transcellular Ca²⁺ transport are recognized:  cellular entry of Ca²⁺ ion on the apical side via TRPV6 (Step-1), the binding of Ca²⁺ ion with calbindin-D₉ₖ (Step-2), and exit of Ca²⁺ from the basolateral side via the plasma membrane Ca²⁺ ATPase (PMCA1b). The hormone Vitamin D₃ (or 1,25(OH)₂D₃) plays an important role in TRPV6-mediated intestinal Ca²⁺ absorption).
caption: Figure 4. Role of TRPV6 in intestinal calcium absorption. TRPV6 mediates Ca2+ entry across the plasma membrane as the first step in the transcellular pathway of Ca2+ transport. This is considered the rate-limiting step in Ca2+ absorption by the enterocytes. The transcellular pathway enables the transport of Ca2+ against a [Ca2+] gradient to ensure Ca2+ absorption when the luminal [Ca2+] is lower than that in the blood side; The Ca2+ binding protein calbindin-D9k and plasma membrane Ca2+ ATPase (PMCA) are known components in these transcellular pathways.
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