Ankyrin repeat

Ankyrin Repeat

An ankyrin repeat is a common protein structural motif that consists of repeating units of approximately 33 amino acids. These repeats are known for their ability to mediate protein-protein interactions and are found in a wide variety of proteins across different species.

Structure

Each ankyrin repeat typically forms a helix-loop-helix structure, where the helices are connected by a loop. The repeats stack together to form a linear array, creating a surface that can interact with other proteins. The consensus sequence of an ankyrin repeat is characterized by a conserved pattern of hydrophobic and polar residues, which contribute to the stability and function of the motif.

Function

Ankyrin repeats are involved in a multitude of cellular processes due to their role in mediating protein-protein interactions. They are found in proteins that participate in signal transduction, cell cycle regulation, transcriptional regulation, and cytoskeletal organization. The versatility of ankyrin repeats allows them to bind to a wide range of target proteins, making them crucial components in cellular signaling pathways.

Examples

Some well-known proteins that contain ankyrin repeats include:

• IκB (Inhibitor of kappa B): A protein that regulates the NF-κB signaling pathway by sequestering NF-κB in the cytoplasm.
• ANK1 (Ankyrin 1): A protein that links the integral membrane proteins to the underlying spectrin-actin cytoskeleton, particularly in erythrocytes.
• Notch receptor: A receptor involved in cell differentiation processes, which contains ankyrin repeats in its intracellular domain.

Evolution

Ankyrin repeats are highly conserved across different species, indicating their evolutionary importance. They are present in both prokaryotic and eukaryotic organisms, suggesting that they arose early in the evolution of life. The conservation of ankyrin repeats across diverse species highlights their fundamental role in cellular function.

Also see

• Protein structure
• Protein-protein interaction
• Signal transduction
• Cytoskeleton
• NF-κB signaling pathway