The omega loop[1][2] is a non-regular protein structural motif, consisting of a loop of six or more amino acid residues and any amino acid sequence. The defining characteristic is that residues that make up the beginning and end of the loop are close together in space with no intervening lengths of regular secondary structural motifs. It is named after its shape, which resembles the upper-case Greek letter Omega (Ω).
- ^ Leszczynski, JF; Rose, GD (14 Nov 1986). "Loops in globular proteins: a novel category of secondary structure". Science. 234 (4778): 849–855. Bibcode:1986Sci...234..849L. doi:10.1126/science.3775366. PMID 3775366.
- ^ Fetrow, JS (June 1995). "Omega loops: nonregular secondary structures significant in protein function and stability". FASEB J. 9 (9): 708–17. doi:10.1096/fasebj.9.9.7601335. PMID 7601335. S2CID 23775489.