Eukaryotic proteins that help some nascent polypeptide chains fold correctly into their tertiary shapes, stabilizing and protecting them in the process, and/or preventing them from making premature or nonproductive intermolecular associations. Note that a chaperone forms a complex with a second protein to facilitate its folding, but chaperones are not part of the mature structure. Some of these molecular chaperones are heat-shock proteins (q.v.). Some chaperones may bind to nascent polypeptide chains while they are being synthesized on ribosomes, and they may also help the polypeptide move out of the tunnel of 60S ribosomal subunit. Other chaperones may keep the polypeptide in an unfolded conformation as it is being translated. This facilitates subsequent passage across membranes, as when protein enters the endoplasmic reticulum or a mitochondrion. Also called chaperonins or molecular chaperones. See prions.
Subjects: Genetics and Genomics — Medicine and Health.