The four helix bundle usually consists of four alpha helices packed in a coil coil arrangement, typically with a hydrophobic core in the center. The alpha helix is classified as secondary structure in a coiled conformation, resembling a spring. Each backbone has a N-H group that donates a hydrogen bond to the backbone C=O group of the amino acid.
1CE9 is involved in the helix capping of the GCN4 leucine zipper. Its molecular function involves transcription factor activity and protein dimerization activity.
2BNI is a general control protein for Gcn4.