Glycophorins and Skeletal Proteins Overview

Which protein is primarily responsible for anchoring the band 3 and protein 4.2 in erythrocyte membranes?

What role does the protein Ankyrin serve in erythrocyte membranes?

Which hereditary condition is associated with a deficiency in Ankyrin and results in a decreased surface area-to-volume ratio of erythrocytes?

Which glycophorin is known to support the determinants of the Gerbich system?

Which of the following skeletal proteins is primarily responsible for regulating actin polymerization in erythrocytes?

What is the inheritance pattern of hereditary spherocytosis?

Which glycophorin is responsible for the transport of urea in erythrocytes?

What major effect does hereditary spherocytosis have on MCHC values?

Glycophorins

Glycophorin A transports negatively charged sialic acid and supports determinants.
Glycophorin B transports negatively charged sialic acid and supports Ss determinants.
Glycophorin C transports negatively charged sialic acid, supports Gerbich system determinants, and integrin adhesion.

Skeletal Proteins

Skeletal proteins provide horizontal or lateral support for the membrane.
They contribute to the shape and flexibility of erythrocytes.
Examples include a-spectrin, β-spectrin, adducin, ankyrin, dematin, F-actin, protein 4.1, protein 4.2, tropomodulin, and tropomyosin.

Skeletal Protein Function

a-spectrin: Primary cytoskeletal protein, forming caps actin filaments.
β-spectrin: Anchors band 3 and protein 4.2, binds β-spectrin.
Adducin: Actin bundling protein.
Ankyrin: Anchors 4.1 complex and anchors ankyrin complex.
Dematin: Caps actin filament.
F-actin: Protein.
Protein 4.1: Anchors 4.1 complex.
Protein 4.2: Caps actin filament and regulates actin polymerization.
Tropomodulin: Caps actin filament.
Tropomyosin: Regulates actin polymerization.

Hereditary RBC Membrane Defects

Hereditary spherocytosis is an autosomal dominant condition (75%).
Deficient proteins include ankyrin, band 3, a-spectrin, β-spectrin, and protein 4.2.
Defects in these proteins disrupt membrane interactions between transmembrane proteins and the underlying cytoskeleton.
This leads to loss of membrane and a decreased surface area-to-volume ratio.
Patients with hereditary spherocytosis may have an increased MCHC (mean corpuscular hemoglobin concentration). A normal MCHC range is 31 to 37 g/dL. Hemoglobin values (MCHC) rise above 35-38 g/dL because of spherocytosis.

This quiz covers key aspects of glycophorins and skeletal proteins, highlighting their functions in red blood cells. Explore the roles of various skeletal proteins in maintaining the membrane structure and flexibility, along with the significance of glycophorins in the transport of sialic acid. Test your understanding of these essential components in erythrocyte physiology.