Leucine-rich repeat
Leucine-rich repeat (LRR) is a structural motif or domain that is involved in the formation of protein-protein interactions. The motif is characterized by a repeating sequence of 20-30 amino acids that are rich in leucine. These repeats often fold together to form a horseshoe-like structure that is involved in the binding of proteins to other molecules. LRRs are found in a variety of proteins, including those involved in the immune response, such as Toll-like receptors, and in the development and functioning of the nervous system.
Structure[edit | edit source]
The leucine-rich repeat structure is typically composed of 2-42 motifs, each of which includes a highly conserved sequence pattern. The consensus sequence is LxxLxLxxN/CxL, where "L" stands for leucine, "N" for asparagine, "C" for cysteine, and "x" for any amino acid. The repeats are usually flanked by cysteine-rich domains, which help in stabilizing the fold. The LRR domain forms an elongated, non-globular structure, with the leucine residues positioned on the interior, contributing to the hydrophobic core, and the more polar residues exposed to the solvent.
Function[edit | edit source]
Leucine-rich repeats are involved in a wide range of functions, primarily related to protein-protein interactions. They play a crucial role in the immune system, where they are part of the recognition sites for pathogens. For example, in Toll-like receptors, LRRs are responsible for recognizing pathogen-associated molecular patterns (PAMPs), leading to the activation of innate immune responses. In addition to immune functions, LRR-containing proteins are involved in signal transduction, cell adhesion, DNA repair, and the regulation of gene expression. Their ability to mediate protein-protein interactions makes them essential for the proper functioning of various cellular processes.
Examples of LRR-Containing Proteins[edit | edit source]
- Toll-like receptors: Involved in the recognition of PAMPs and the initiation of immune responses. - NOD-like receptors: Play a role in the immune system by recognizing intracellular pathogens and initiating inflammatory responses. - SLIT-ROBO Rho GTPase activating proteins: Involved in axon guidance and neuronal development. - Glycoprotein Ib: A platelet membrane protein involved in blood clotting.
Evolution[edit | edit source]
The LRR motif is highly conserved across a wide range of organisms, from plants and bacteria to mammals, indicating its fundamental importance in biological systems. The evolutionary conservation of the LRR motif suggests that it provides a versatile structural framework for protein-protein interactions, adaptable to various functional contexts. The diversity of LRR-containing proteins and their roles in different biological processes reflect the evolutionary adaptation of this motif to meet the specific interaction needs of the organism.
Research and Clinical Implications[edit | edit source]
Understanding the structure and function of LRR-containing proteins has significant implications for the development of therapeutic interventions. For example, modulating the activity of Toll-like receptors can potentially treat autoimmune diseases or enhance the immune response against pathogens. Additionally, the role of LRR-containing proteins in neuronal development and function suggests that they could be targets for the treatment of neurological disorders.
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