The heptad repeat is an example of a structural motif that consists of a repeating pattern of seven amino acids:[1]
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.[2]
A conformational change in a heptad repeat in the SARS-CoV-2 spike protein facilitates entry of the virus into the host cell membrane.[3]
References[edit]
- ^ Seroski, Dillon T.; Hudalla, Gregory A. (2018). "Self-Assembled Peptide and Protein Nanofibers for Biomedical Applications". Biomedical Applications of Functionalized Nanomaterials. pp. 569–598. doi:10.1016/B978-0-323-50878-0.00019-7. ISBN 978-0-323-50878-0.
- ^ Chambers P, Pringle CR, Easton AJ (1990). "Heptad repeat sequences are located adjacent to hydrophobic regions in several types of virus fusion glycoproteins". The Journal of General Virology. 71 (12): 3075–80. doi:10.1099/0022-1317-71-12-3075. PMID 2177097.
- ^ Jackson CB, Farzan M, Chen B, Choe H (2022). "Mechanisms of SARS-CoV-2 entry into cells". Nature Reviews Molecular Cell Biology. 23 (1): 3–20. doi:10.1038/s41580-021-00418-x. PMC 8491763. PMID 34611326.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction