An example of a leucine-rich repeat protein, a porcine ribonuclease inhibitor
Identifiers
Symbol	LRR_1
Pfam	PF00560
InterPro	IPR001611
SCOP	2bnh
OPM protein	1xwd
Available PDB structures: 1ogqA:155-177 1jl5A:358-382 1g9uA:358-382 1k5dF:123-149 2ca6A:123-149 1yrgA:123-149 1k5gF:123-149 1k15A:165-187 1m0zA:165-187 1u0nD:165-187 1qyyG:165-187 1sq0B:165-187 1m10B:165-187 1ookG:165-187 1k13A:165-187 1p9aG:165-187 1p8vA:165-187 1k14A:165-187 1ziwA:563-585 2a0zA:563-585 1wwlA:292-318 1p8tA:131-153 1oznA:131-153 1xum :54-75 1xcdA:131-149 1xecB:131-149 1xkuA:131-149 1xwdC:194-217 1xun :194-217 1o6sA:274-294 1kohB:292-315 1fo1B:292-315 1ft8D:292-315 1kooC:292-315 2bnh :337-360 1dfjI:337-360 1a4yD:114-137 2bexA:114-137 1z7xW:114-137 1dceA:509-532 1ltxA:509-532 1p95B:551-560 1xeuA:162-182 1m9lA:116-139 1ds9A:116-139 1m9sA:165-185 1h6tA:165-185 1otmA:165-185 1otoA:165-185 1d0bA:165-185 1otnA:165-185 1h6uA:209-229 1w8aA:596-618 1a9nA:89-109

A leucine-rich repeat (LRR) is a protein structural motif that forms an α/β horseshoe fold.^[1][2] It is composed of repeating 20-30 amino acid stretches that are unusually rich in the hydrophobic amino acid leucine. Typically, each repeat unit has beta strand-turn-alpha helix structure, and the assembled domain, composed of many such repeats, has a horseshoe shape with an interior parallel beta sheet and an exterior array of helices. One face of the beta sheet and one side of the helix array are exposed to solvent and are therefore dominated by hydrophilic residues. The region between the helices and sheets is the protein's hydrophobic core and is tightly sterically packed with leucine residues.

Leucine-rich repeats are frequently involved in the formation of protein-protein interactions.^[3][4]

[edit] Examples

Leucine-rich repeat motifs have been identified in a large number of functionally unrelated proteins.^[5] The best-known example is the ribonuclease inhibitor, but other proteins such as the tropomyosin regulator tropomodulin and the toll-like receptor also share the motif. In fact, the toll-like receptor possesses 10 successive LRR motifs which serve to bind antigen.

Although the canonical LRR protein contains approximately one helix for every beta strand, variants that form beta-alpha superhelix folds sometimes have long loops rather than helices linking successive beta strands.

[edit] See also

• Leucine zipper

[edit] References

[edit] Further reading

• Tooze, John; Brändén, Carl-Ivar (1999). Introduction to Protein Structure (2nd ed. ed.). New York: Garland Publishing. ISBN 0-8153-2305-0. 
• Wei T, Gong J, Jamitzky F, Heckl WM, Stark RW, Roessle SC (November 2008). "LRRML: a conformational database and an XML description of leucine-rich repeats (LRRs)". BMC Struct. Biol. 8 (1): 47. doi:10.1186/1472-6807-8-47. PMID 18986514. 

[edit] External links

• SCOP LRR fold
• CATH Alpha-beta horseshoe architecture
• LRRML: a conformational database of leucine-rich repeats

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