coiledcoilcontaining

Coiled-coil containing refers to proteins or protein domains that include one or more coiled-coil motifs—a structural arrangement in which two or more alpha helices wrap around each other to form a supercoil. In canonical coiled-coils, heptad repeats (abcdefg) position hydrophobic residues at a and d, creating a hydrophobic core that stabilizes the interaction. These motifs often extend as long, rod-like segments and may be interrupted by linkers or other domains.

Coiled-coil regions mediate protein–protein interactions and enable dimerization or oligomerization, serving as scaffolds in the cytoskeleton, vesicle trafficking, and nuclear architecture. They are central to the function of intermediate filament proteins (keratins, vimentin, lamins), myosin rod domains, and various motor and adaptor complexes. In transcription, coiled-coil domains appear in many regulators, notably leucine-zipper and some bZIP proteins, where the motif facilitates dimerization and partner interactions.

Prediction and identification of coiled-coil containing segments are routine in sequence analysis, using tools that detect heptad repeats and periodic hydrophobic residues. Coiled-coil motifs are evolutionarily widespread and versatile, found in bacteria and eukaryotes. Clinically significant mutations in coiled-coil regions can disrupt assembly and cause disease, including laminopathies from LMNA mutations and skin disorders linked to keratin defects.

While coiled-coil containing describes proteins with substantial coiled-coil stretches, many proteins harbor shorter coiled-coil segments as part of larger folds or multifunctional domains. The term can also appear in database annotations describing proteins that possess one or more coiled-coil regions.