This complex recognizes and catalyzes the release of the nascent polypeptide chain when the ribosome encounters a stop codon.
Partial loss of function results in nonsense suppression, in which stop codons are ignored and proteins are abnormally synthesized with carboxyl terminal extensions.
This results in less soluble and functional protein and thus in an increased rate of nonsense suppression (translational read-through of stop codons).
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.
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.
In modified versions of the gene, it has been shown that the more repeats of this sequence present, the more the protein is to assume the [Psi+] confirmation.
Because CAIR converts back into AIR if the enzyme that catalyzes it to the next precursor is absent, either mutation will cause a red color in the [psi-] strain.