Motif Structures of Transcription Factors

Most transcription factors contain a specific motif for interaction with DNA.  The following motifs are commonly observed:

Zinc finger
It contains one or more zinc ions which are crucial for the structural stability.

Helix-Turn-Helix
It consists of two a helices and a short extended amino acid chain between them.

Leucine zipper
It is formed by two a helices, which are held together by hydrophobic interactions between leucine residues.

Helix-Loop-Helix
It is characterized by two a helices connected by a loop.

Review Article:

Designing Transcription Factor Architectures for Drug Discovery - Mol. Pharma., 2004.