Editing Sup35p (section)

== Evolutionary capacitance ==
Several journal articles have suggested that the ability to interconvert between [PSI+] and [psi-](prion-free) states provides an evolutionary advantage, but this remains an area of much debate.

[[Susan Lindquist]] has shown that [[Zygosity|isogenic]] populations of yeast can express different phenotypes based on whether they had the prion form of Sup35p or the non-prion form. She did an experiment where seven strains of yeast with different genetic backgrounds were grown under many different stressful conditions, with matched [PSI+] and [psi-] strains.<ref name="pmid11028992">{{cite journal | vauthors = True HL, Lindquist SL | title = A yeast prion provides a mechanism for genetic variation and phenotypic diversity | journal = Nature | volume = 407 | issue = 6803 | pages = 477–83 | date = September 2000 | pmid = 11028992 | doi = 10.1038/35035005 | bibcode = 2000Natur.407..477T | s2cid = 4411231 }}</ref> In some cases, the [PSI+] version grew faster, in others [psi-] grew faster. She proposed that [PSI+] may act as an [[evolutionary capacitor]] to facilitate adaptation by releasing cryptic genetic variation in natural populations at times of stress. This variation would lie beyond stop codons, which show a high rate of in-frame loss in yeast.<ref>{{cite journal |doi=10.1093/molbev/msl172 |vauthors=Giacomelli M, Hancock AS, Masel J |title=The conversion of 3′ UTRs into coding regions |journal=Molecular Biology and Evolution |volume=24 |pages=457–464 |year=2007 |pmid=17099057 |pmc=1808353 |issue=2}}</ref> Mathematical models suggest that [PSI+] may have evolved for this function.<ref>{{cite journal |vauthors=Masel J, Bergman A |title=The evolution of the evolvability properties of the yeast prion [PSI+] |journal=Evolution |volume=57 |issue=7 |pages=1498–1512 |year=2003 |pmid=12940355 |doi=10.1111/j.0014-3820.2003.tb00358.x|s2cid=30954684 }}</ref>