AlphaBeta Loop

Motif Glossary

BulgeLoop Motif

Definition

A motif of five or six residues formed by a composite of a Beta Bulge Loop and an Asx- or ST-motif in one of the following two ways:

• BulgeLoop Motif (5-residue) with Asx- or ST-motif (sc 1-3, 1-4)
• BulgeLoop Motif (6-residue) with Asx- or ST-motif (sc 1-4, 1-4)

Sub-categories

There are sub-categories to distinguish between Asp, Asn, Ser and Thr for the 5- and 6-residue variants.

Reference

Afzal et al., Proteins 82:3023–3031 (2014)

Comments

1. The 5-residue BulgeLoop Motifs contain an N1N3-bridged nest in which the O atom of the side-chain is the acceptor. They contain four hydrogen bonds in total.

2. The 6-residue BulgeLoop Motifs contain an N2N3-bridged nest in which the main-chain O atom of Asx or ST is the acceptor. They contain four hydrogen bonds in total.

3. The 5-residue BulgeLoop Motifs are similar to Schellman loops in their backbone architecture and hydrogen bonding.

Occurrence

1. BulgeLoop Motifs occur in approx. 25% of proteins.

2. All the 6-residue BulgeLoop Motifs in our database are of the Asx sub-categories.

Introduction AlphaBeta Loop Asx Motif Asx Turn Beta Bulge Beta Bulge Loop Beta Link Beta Turn BulgeLoop Motif Crown Bridge Crown Bridge Loop Nest Niche Schellman Loop ST Loop ST Motif ST Staple ST Turn