Transferriin

Transferriin is not a widely recognized term in contemporary biochemistry. In most current literature, the iron-transport protein responsible for systemic iron distribution is transferrin (TF). The spelling “transferriin” may reflect a typographical variant, an older usage, or confusion with related proteins such as the transferrin receptor. The article that follows uses transferrin to describe the component typically intended by the term transferriin.

Transferrin is a high-affinity iron-binding glycoprotein found in blood plasma. It binds ferric iron (Fe3+) and serves as the main transporter that delivers iron to cells throughout the body. Iron-loaded transferrin binds to transferrin receptors on cell surfaces and is taken into cells by receptor-mediated endocytosis. Within acidic endosomes, iron is released, and apo-transferrin is recycled back to the plasma to participate in another transport cycle. Transferrin levels and iron status together help regulate iron homeostasis and distribution to tissues such as the bone marrow, liver, and brain.

Structure and properties: transferrin is typically a single polypeptide of about 80 kilodaltons, composed of two homologous lobes (N-lobe and C-lobe). Each lobe can bind one Fe3+ ion, often with a synergistic anion such as carbonate aiding binding. The protein is glycosylated, which influences its stability and pharmacokinetics in circulation.

Clinical relevance: serum transferrin concentration and the fraction of transferrin bound to iron (transferrin saturation) are commonly used to assess iron status. Low transferrin saturation suggests iron deficiency, while changes in transferrin levels can occur with inflammation, pregnancy, or liver disease. If the goal is to discuss a specific molecule named transferriin, standard references should be consulted, as the canonical term is transferrin.