Gastric parietal cells secrete gastric intrinsic factor (GIF) which binds tightly to free cobalamin (Cbl) released from transcobalamin (TCN1, haptocorrin) in the proximal intestine (Matthews et al. 2007). Cbl must bind to GIF to be absorbed from the small intestine.
Mathews, FS, Gordon, MM, Chen, Z, Rajashankar, KR, Ealick, SE, Alpers, DH, Sukumar, N
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