Heptad repeat

The '''heptad repeat''' is an example of a structural motif that consists of a repeating pattern of seven amino acids:<ref>{{cite book |doi=10.1016/B978-0-323-50878-0.00019-7 |chapter=Self-Assembled Peptide and Protein Nanofibers for Biomedical Applications |title=Biomedical Applications of Functionalized Nanomaterials |year=2018 |last1=Seroski |first1=Dillon T. |last2=Hudalla |first2=Gregory A. |pages=569–598 |isbn=978-0-323-50878-0 }}</ref>

''a b c d e f g'' '''H''' P P '''H''' C P C

where '''H''' represents hydrophobic residues, C represents, typically, charged residues, and P represents polar (and, therefore, hydrophilic) residues. The positions of the heptad repeat are commonly denoted by the lowercase letters ''a'' through ''g''.

These motifs are the basis for most coiled coils and, in particular, leucine zippers, which have predominantly leucine in the ''d'' position of the heptad repeat.<ref>{{cite journal |vauthors=Chambers P, Pringle CR, Easton AJ |title=Heptad repeat sequences are located adjacent to hydrophobic regions in several types of virus fusion glycoproteins |journal=The Journal of General Virology |volume=71 |issue=12 |pages=3075–80 |year=1990 |pmid=2177097 |doi=10.1099/0022-1317-71-12-3075 |doi-access=free }}</ref>

A conformational change in a heptad repeat in the SARS-CoV-2 spike protein facilitates entry of the virus into the host cell membrane.<ref name="pmid34611326">{{cite journal | vauthors = Jackson CB, Farzan M, Chen B, Choe H | title = Mechanisms of SARS-CoV-2 entry into cells | journal = Nature Reviews Molecular Cell Biology | volume = 23 | issue=1 | pages = 3–20 | date = 2022 | doi = 10.1038/s41580-021-00418-x | pmc = 8491763 | pmid = 34611326}}</ref>

==References== {{reflist}}

{{DEFAULTSORT:Heptad Repeat}} Category:Protein structural motifs