Question

Which of the common structural motifs are described wrongly?

(a) β-hairpin – adjacent antiparallel strands

(b) Greek key – 4 adjacent antiparallel strand

(c) β-α-β – 2 parallel strands connected by helix

(d) β-α-β – 2 antiparallel strands connected by helix

Answer 1

Right choice is (d) β-α-β – 2 antiparallel strands connected by helix

To elaborate: In motif, two adjacent β  parallel strands are connected by an α helix from the C-terminus of strand 1 to the N-terminus of strand. Most protein structures that contain parallel beta-sheets are built up from combinations of such β-α-βmotifs.