Editing Protein folding (section)

=== Fold switching ===
Some proteins have multiple native structures, and change their fold based on some external factors. For example, the KaiB protein [[KaiB#Circadian outputs and KaiB fold switching|switches fold throughout the day]], acting as a clock for cyanobacteria. It has been estimated that around 0.5&ndash;4% of PDB ([[Protein Data Bank]]) proteins switch folds.<ref>{{cite journal |last1=Porter |first1=Lauren L. |last2=Looger |first2=Loren L. |title=Extant fold-switching proteins are widespread |journal=Proceedings of the National Academy of Sciences |date=5 June 2018 |volume=115 |issue=23 |pages=5968–5973 |doi=10.1073/pnas.1800168115 |pmid=29784778 |pmc=6003340 |bibcode=2018PNAS..115.5968P |doi-access=free}}</ref>