The structure and function of band 3 (AE1): recent developments (review)

Area of Science:

• Membrane biology
• Molecular genetics
• Red blood cell physiology

Background:

• Band 3 (AE1) is a crucial protein in red blood cell membranes, involved in anion exchange.
• Understanding its structure and function is key to comprehending associated diseases.
• Previous models of band 3 topology have been refined by recent research.

Purpose of the Study:

• To review recent advances in the structure, function, and molecular genetics of the red cell anion exchanger band 3 (AE1).
• To explore the role of band 3 in red cell and kidney diseases.
• To present a new model for band 3 topology and discuss disease-associated mutations.

Main Methods:

• Analysis of two-dimensional crystals of the deglycosylated membrane domain of band 3.
• Sequencing of the human band 3 gene to study mutations.
• Review of clinical data on hereditary spherocytosis, ovalocytosis, and renal tubular acidosis linked to band 3.

Main Results:

• A new model proposes 12 membrane spans for band 3, differing in C-terminal topology.
• Band 3 mutations are implicated in approximately 20% of hereditary spherocytosis cases.
• Novel band 3 mutations are linked to familial distal renal tubular acidosis.
• Band 3 is not essential for life, as shown by animal studies with total absence of the protein.

Conclusions:

• Band 3's membrane domain structure has been refined, impacting our understanding of its function.
• Mutations in band 3 are significant causes of inherited red cell disorders and kidney diseases.
• Band 3 stabilizes the red cell membrane bilayer through interactions with lipids, not solely the spectrin skeleton.