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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:

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BulgeLoop Motif-5   BulgeLoop Motif-6

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.