Structural motif

In an unbranched, chain-like biological molecule, such as a protein or a strand of RNA, a structural motif is a three-dimensional structural element or fold within the chain, which appears also in a variety of other molecules. In the context of proteins, the term is sometimes used interchangeably with "structural domain," although a domain need not be a motif nor, if it contains a motif, need it be made up of only one.

Related Topics:
Chain-like - Molecule - Protein - RNA - Fold - Structural domain

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Structural alignment is a major method for discovering significant structural motifs.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Motifs exhibit both tertiary and secondary structure, and may be regarded as a configuration of secondary structures. Such a description is the basis for many of the names that structural biologists give to particular kinds, such as the helix-turn-helix motif. This is not always true, however, as in the case of the EF-hand.

Related Topics:
Tertiary - Secondary structure - Structural biologists - EF-hand

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Because the relationship between primary structure and tertiary structure is not straight forward, two biopolymers may share the same motif yet lack appreciable primary structure similarity. In other words, a structural motif need not be associated with a sequence motif. Also, the existence of a sequence motif does not necessarily imply a distinctive structure. In most DNA motifs, for example, it is assumed that the DNA of that sequence does not deviate from the normal "double helical" structure.

Related Topics:
Primary structure - Sequence motif - Double helical

~ ~ ~ ~ ~ ~ ~ ~ ~ ~