Contents

Search

ferritin

Function: - major iron storage compound - in hepatocytes & in the macrophage system of the bone marrow & other organs, ferritin provides a reserve of iron readily available for the formation of heme proteins Structure: - spherical complex consisting of an apoferritin shell & an interior of [FeOOH]x crystallin core [2] - another source suggests stored iron is in the form Fe[O{H2PO4}] - the apoferritin shell consists of ~ 24 subunits [variable number of light chains & heavy chains] - in human liver the heavy chain is the major chain - ferritin is about 13 nm in diameter with a central cavity of 7 nm in diameter. - 6 pores approximately 0.7-1.0 nm in diameter permit diffusion of small molecules, significantly FMN, ascorbate, & Fe+2 - the edges of the pores serve as redox sites for influx & efflux of Fe+2 with storage of FeOOH in the core crystal - he core crystal may contain as many as 4000 Fe atoms, but usually contains 1/2 or less that many [2] Expression: - ferritin is found in nearly all cells of the body - in men, the total body content of stored iron, mostly as ferritin is 800 mg - in healthy women, it ranges from 0-200 mg - minute quantities of ferritin are also present in serum in proportion to total body iron stores, with 1 ng/mL indicating 8 mg of total body iron Pathology: - serum ferritin levels are increased in relation to total iron stores in fasting, inanition, burns, chronic inflammatory disorders, infections, neoplasms, & in chronic renal disease, increasing the ratio of 1 ng/mL:8 mg total body iron, thus overestimating the total body iron stores. - ferritin levels < 10 ng/mL usually indicate iron deficiency anemia

Related

ferritin in serum/plasma

Specific

hemosiderin

General

acute phase protein metalloprotein molecular complex

Properties

SIZE: MW = 460 kD COMPARTMENT: plasma MOTIF: Iron [Fe]-binding site (4500) EFFECTOR-BOUND: FE[O{H2PO4}] SUBUNITS: ferritin heavy chain (12) MOTIF: Ferritin-like diiron {11-160} MOTIF: Iron [Fe]-binding site SITE: 28-28 Iron [Fe]-binding site SITE: 63-63 Iron [Fe]-binding site SITE: 66-66 Iron [Fe]-binding site SITE: 108-108 Iron [Fe]-binding site SITE: 142-142 Ser phosphorylation site {S179} ferritin light chain (12) MOTIF: Ferritin-like diiron {7-156} MOTIF: active site SITE: 54-61 Iron [Fe]-binding site SITE: 54-54 Iron [Fe]-binding site SITE: 57-57 Iron [Fe]-binding site SITE: 58-58 Iron [Fe]-binding site SITE: 61-61 Iron [Fe]-binding site SITE: 64-64

References

  1. Tietz Textbook of Clinical Chemistry, 2nd ed. Burtis CA & Ashwood ER (eds), WB Saunders Co, Philadelphia PA, 1993, pg 2060
  2. Wikipedia; Note: ferritin entry http://en.wikipedia.org/wiki/ferritin

Components

ferritin heavy chain (ferritin H subunit, cell proliferation-inducing gene 15 protein, FTH1, FTH, FTHL6, OK/SW-cl84, PIG15) ferritin light chain; ferritin L subunit (FTL)