Gastrointestinal calcium absorption

Gastrointestinal calcium absorption is not a single molecule or receptor, but rather a physiological process by which dietary calcium is taken up from the intestinal lumen into the body. This occurs through two main mechanisms: 1. Transcellular active transport: Predominantly in the duodenum and upper jejunum. It involves entry through apical channels such as TRPV6 (formerly CaT1), intracellular binding to calbindin-D9k, and extrusion across the basolateral membrane via plasma membrane Ca²⁺ ATPase (PMCA). This pathway is tightly regulated by vitamin D—specifically its active metabolite 1,25(OH)₂D₃—which increases expression of key proteins involved in this route[1][3][4][5]. 2. Paracellular passive diffusion: Occurs throughout the small intestine when luminal concentrations are high enough for passive movement between enterocytes via tight junctions. This mechanism is non-saturable and less regulated than transcellular transport[3][7]. The efficiency of gastrointestinal calcium absorption depends on factors including dietary intake level, age, hormonal status (especially vitamin D), intestinal transit time, pH affecting solubility, presence of inhibitors like phytates/oxalates/tannins in food[3], and genetic polymorphisms affecting transporter proteins. While not itself a druggable target or receptor/enzyme/transporter/protein family member—and thus not considered an individual therapeutic target—the underlying molecular components such as TRPV6, calbindin-D9k, plasma membrane Ca²⁺ ATPase, and regulatory elements like the vitamin D receptor are recognized targets for research into bone health disorders including osteoporosis[4][5]. In summary: "Gastrointestinal calcium absorption" refers to an essential physiological function involving multiple coordinated molecules rather than being itself a canonical drug target or molecular entity suitable for structured annotation under typical pharmacological frameworks.

Other names

Intestinal calcium absorptionIntestinal Ca2+ absorptionCalcium uptake in the gutGI calcium absorption

Mechanisms involve modulation of underlying transporters, channels, and regulatory pathways such as vitamin D analogs increasing transcellular transport via upregulation of TRPV6 and calbindin-D9k[1][3][4][5].