This is a Ribonuclease Inhibitor Protein that illustrates the horseshoe fold. It contains the LRR: Leucine Rich Repeat. The leucines are packed between the beta-strands and the alpha-helices. Kobe, B., Deisenhofer, J.: A structural basis of the interactions between leucine-rich repeats and protein ligands. Nature 374 pp. 183 (1995) (PubMed) 1dfj (PDB)