Which molecule binds to iron for cellular uptake once it is released from the enterocyte?

Transferrin is a glycoprotein responsible for the transport of iron in the bloodstream. Once iron is released from enterocytes (intestinal cells that absorb nutrients), it does not circulate freely due to its potential for generating free radicals. Instead, it binds to transferrin, which has specific high-affinity binding sites for iron ions. This complex ensures safe and efficient transport of iron to various tissues and organs where it is needed, such as the liver, spleen, and bone marrow.

Hemosiderin, while an iron-storage complex, is not involved in the transport of iron immediately following absorption. Ferritin serves as a storage form of iron within cells, allowing for iron to be stored in a non-toxic form; however, it does not facilitate iron transport in the bloodstream. Heme is a form of iron that is incorporated into hemoglobin but is not the molecule responsible for iron transport following absorption in the intestine. Therefore, transferrin is the correct answer as it directly handles the transport of iron once it has been absorbed into the body.