Protein structural motifs

The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a righthand-coiled or spiral conformation (helix) in which every backbone N-H group donates a hydrogen bond to the backbone C=O group of the amino acid located three or four residues earlier along the protein sequence.

A zinc finger is a small protein structural motif that is characterized by the coordination of one or more zinc ions in order to stabilize the fold.

F-box proteins are proteins containing at least one F-box domain.

A basic helix-loop-helix (bHLH) is a protein structural motif that characterizes a family of transcription factors.

Granin (chromogranin and secretogranin) is a protein family of regulated secretory proteins ubiquitously found in the cores of amine and peptide hormone and neurotransmitter dense-core secretory vesicles.

The inhibitor of apoptosis domain -- also known as IAP repeat, Baculovirus Inhibitor of apoptosis protein Repeat, or BIR -- is a structural motif found in proteins with roles in apoptosis, cytokine production, and chromosome segregation.

In proteins, the helix-turn-helix (HTH) is a major structural motif capable of binding DNA.

In molecular biology, a RING (Really Interesting New Gene) finger domain is a protein structural domain of zinc finger type which contains a C3HC4 amino acid motif which binds two zinc cations (seven cysteines and one histidine arranged non-consecutively).

In molecular biology, the protein domain Sterile alpha motif (or SAM) is a putative protein interaction module present in a wide variety of proteins involved in many biological processes.

In collagen, the collagen helix, or type-2 helix, is a major shape in secondary structure.

The EF hand is a helix-loop-helix structural domain or motif found in a large family of calcium-binding proteins.

The PHD finger was discovered in 1993 as a Cys4-His-Cys3 motif in the plant homeodomain (hence PHD) proteins HAT3.

Pentapeptide repeats are a family of sequence motifs found in multiple tandem copies in protein molecules.

The ankyrin repeat is a 33-residue motif in proteins consisting of two alpha helices separated by loops, first discovered in signaling proteins in yeast Cdc10 and Drosophila Notch.

The Kelch motif is a region of protein sequence found widely in proteins from bacteria and eukaryotes.

In molecular biology, the Ubiquitin-Interacting Motif (UIM), or 'LALAL-motif', is a sequence motif of about 20 amino acid residues, which was first described in the 26S proteasome subunit PSD4/RPN-10 that is known to recognise ubiquitin.