Which protein is NOT a tethering protein of the red blood cell membrane?

Which protein is NOT a tethering protein of the red blood cell membrane?

• A. Spectrin
• B. Band 3.1
• C. Ankyrin
• D. Glycophorin

Answer: (D)

Red blood cell membrane stability relies on a spectrin-based cytoskeleton that is anchored to the membrane by tethering proteins. Spectrin forms a lattice under the membrane, ankyrin bridges spectrin to the transmembrane protein band 3, and protein 4.1 helps connect the cytoskeleton to glycophorin and band 3, reinforcing the linkage. Glycophorin itself is a transmembrane glycoprotein that mainly serves as a surface antigen and participates in cell interactions; it is not a primary tethering protein of the cytoskeletal framework. Thus, glycophorin is the component that does not function as a tethering protein in this system.

Red blood cell membrane stability relies on a spectrin-based cytoskeleton that is anchored to the membrane by tethering proteins. Spectrin forms a lattice under the membrane, ankyrin bridges spectrin to the transmembrane protein band 3, and protein 4.1 helps connect the cytoskeleton to glycophorin and band 3, reinforcing the linkage. Glycophorin itself is a transmembrane glycoprotein that mainly serves as a surface antigen and participates in cell interactions; it is not a primary tethering protein of the cytoskeletal framework. Thus, glycophorin is the component that does not function as a tethering protein in this system.