Motif Glossary

Asx Motif

Definition

A motif of five consecutive residues and two H-bonds in which there is:

• Aspartate or Asparagine (Asx) at residue-1
• H-bond between side-chain O of residue-1 and main-chain NH of residue-3 or -4
• H-bond between main-chain CO of residue-1 and main-chain NH of residue-4 or -5

Show 3D view

sc1-3, 1-4   sc1-3, 1-5   sc1-4, 1-4   sc1-4, 1-5

Sub-categories

These encompass the four different possible patterns of hydrogen bonding for each of Asp and Asn:

• sc1-3, 1-4
• sc1-3, 1-5
• sc1-4, 1-4
• sc1-4, 1-5

(sc = side-chain)

Reference

Wan and Milner-White, J. Mol. Biol. 286:1633-1649 (1999)

Comment

1. The total number of Asx Motifs is less than the sum of the instances of the sub-categories as individual instances of the motif with an additional mainchain–mainchain H-bond can fall into more than one sub-category.

2. The Asx Motif is analogous to the ST Motif, with the oxygen of the acid or amide side-chain replacing that of the hydroxyl.

Occurrence

The motif is most often found at the N-termini of α-helices.