Tomer Meirson and Abraham O. Samson: κ-helix and the helical lock and key model: A pivotal way of looking at polyproline II (Bioinformatics)
Polyproline II (PPII) is a common conformation, comparable to α-helix and β-sheet and is a candidate for being the most prevalent secondary structure. PPII, recently termed with a more generic name - κ-helix, adopts a left-handed structure with 3-fold rotational symmetry. Lately, a new type of binding mechanism - the helical lock and key model was introduced in SH3-domain complexes, where the interaction is characterized by a sliding helical pattern. However, whether this binding mechanism is unique only to SH3 domains is unreported.