An Absorbing Tale

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Science  15 Dec 2006:
Vol. 314, Issue 5806, pp. 1659
DOI: 10.1126/science.314.5806.1659c

Folate is a water-soluble vitamin that plays a critical role in metabolism. Because humans cannot synthesize it biochemically, they must obtain it by ingestion from folate-rich dietary sources. Maternal folate deficiency has been associated with an elevated risk of neural tube defects in the developing embryo, which can lead to malformations of the spine (such as spina bifida), skull, and brain. Because of these public health issues, there is considerable interest in understanding the specific molecular mechanisms that the body uses to absorb folate from food.

Through a combination of database mining, cell biology, and human genetic analysis, Qiu et al. have identified a transporter protein that appears to be responsible for the intestinal absorption of folate. Previously isolated as heme carrier protein HCP1, the proton-coupled folate transporter (PCFT) was expressed in the small intestine, bound folate with high affinity, and transported folate efficiently into cultured cells at the low pH that characterizes the intestinal milieu. An inactivating mutation in the corresponding gene was identified as the molecular culprit in a family with hereditary folate malabsorption. — PAK

Cell 127, 917 (2006).

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