[3] Many coiled coil-type proteins are involved in important biological functions, such as the regulation of gene expression — e.g., transcription factors.
Eventually, after some controversy and frequent correspondences, Crick's lab declared that the idea had been reached independently by both researchers, and that no intellectual theft had occurred.
[7][8] Based on sequence and secondary structure prediction analyses identified the coiled-coil domains of keratins.
The most favorable way for two such helices to arrange themselves in the water-filled environment of the cytoplasm is to wrap the hydrophobic strands against each other sandwiched between the hydrophilic amino acids.
The packing in a coiled-coil interface is exceptionally tight, with almost complete van der Waals contact between the side-chains of the a and d residues.
Their primary feature is to facilitate protein-protein interaction and keep proteins or domains interlocked.
Viral entry into CD4-positive cells commences when three subunits of a glycoprotein 120 (gp120) bind to CD4 receptor and a coreceptor.
A spring-loaded mechanism is responsible for bringing the viral and cell membranes in close enough proximity that they will fuse.
The origin of the spring-loaded mechanism lies within the exposed gp41, which contains two consecutive heptad repeats (HR1 and HR2) following the fusion peptide at the N terminus of the protein.
[20] Finally, there are several proteins with coiled-coil domains involved in the kinetochore, which keeps chromosomes separated during cell division.
[28][29] Harbury et al. performed a landmark study using an archetypal coiled coil, GCN4, in which rules that govern the way that peptide sequence affects the oligomeric state (that is, the number of alpha-helices in the final assembly) were established.
This effect is due to a self-complementary hydrogen bonding between these residues, which would go unsatisfied if an N were paired with, for instance, an L on the opposing helix.
[33] Coiled-coil motifs have been experimented on as possible building block for nanostructures, in part because of their simple design and wide range of function based primarily on facilitating protein-protein interaction.
Coiled-coil domains can be made to bind to specific proteins or cell surface markers, allowing for more precise targeting in drug delivery.
[35] Other functions would be to help store and transport drugs within the body that would otherwise degrade rapidly, by creating nanotubes and other structure svia the interlocking of coiled-coil motifs.
[34] By utilizing the function of oligomerization of proteins via coiled-coil domains, antigen display can be amplified in vaccines, increasing their effectiveness.
[37] Using peptides with coiled-coil motifs for scaffolding has made it easier to create 3D structures for cell culturing.