Which type of conjugated protein is ferritin?
phosphoprotein
metalloprotein
hemoprotein
flavoprotein
The correct answer and explanation is:
The correct answer is metalloprotein.
Explanation:
Ferritin is a type of metalloprotein because it contains a metal ion, specifically iron, as part of its structure. Metalloproteins are proteins that contain a metal ion, either as a cofactor or as part of the protein’s structure. Ferritin is an iron-storage protein, and it stores iron in a bioavailable and safe form within its hollow structure. The protein is composed of 24 subunits that form a spherical structure capable of storing iron in the form of Fe(III) (ferric) ions.
The iron in ferritin is stored in a mineral form, called ferrihydrite, inside the protein’s core. This allows the body to store iron and release it when needed for various physiological processes, such as red blood cell production. Ferritin plays a crucial role in regulating iron homeostasis by preventing iron toxicity and ensuring that iron is available for processes like hemoglobin synthesis, which requires iron for proper function.
Why not other options?
- Phosphoprotein: A phosphoprotein contains phosphate groups attached to its amino acids. Ferritin does not primarily function by incorporating phosphate groups, so it is not classified as a phosphoprotein.
- Hemoprotein: Hemoproteins contain a heme group, which is a porphyrin ring complexed with iron. While ferritin contains iron, it does not have a heme group and is therefore not classified as a hemoprotein.
- Flavoprotein: Flavoproteins contain a flavin group, derived from riboflavin (vitamin B2). Ferritin does not contain a flavin moiety and is not classified as a flavoprotein.
Thus, ferritin’s role as an iron storage protein, with its metal ion incorporated in its structure, places it under the category of metalloproteins.