Chaperones

One of the most intriguing group of proteins is a group of proteins that assist in the folding and unfolding of macromolecular structures into the correct 3D-architecture, prevents protein clumping and transport damaged or improperly made proteins to be recycled. The chaperones (a lot of them are also known as heat-shock proteins)

Great video

New Insights Into Hidden World Of Protein Folding

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"Folding is one of the key steps for the health of the cell," Frydman said. Virtually all proteins have to be folded-some in complex configurations-in order to function properly, and many are known to require a molecule called a chaperone to fold them. Frydman estimates that perhaps 10 percent of the proteins needing chaperones must have one that, like TRiC, is part of the subset called chaperonins. Other work done in Frydman's lab has shown that proteins that have very complex folds seem to require chaperonins. "Many of the proteins that have these complex folds are the most important ones for life," Frydman said. "The proteins that control the cell cycle, tumor suppressers and the proteins that control the shape of the cell are dependent on chaperonins to get to the folded state. "If the chaperones don't work well, then all these proteins that have been made become toxic," she said.

Protein 'Shocks' Evolution Into Action

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“One of the great mysteries of biology is how life could have evolved so rapidly,” says Lindquist. “This research gives at least one plausible explanation for the speed of evolution and for the evolution of complex traits affected by several genes.”

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“One stressful event can affect many traits and allow previously unseen genetic variation to be expressed,” says Sangster. “We don’t know yet what is going on at the molecular level—why the HSP90-dependent traits are expressed when the plants are mildly stressed.”

Seeing that the structure and functionality of sliding clamps and clamp loaders (not an isolated case btw) are conserved across the three domains of life with very little sequence similarity it seems reasonable that chaperones played a part in conserving the structure and functionality of selected proteins over deep time while retaining flexibility and allowing sequence variability.
This ties in nicely with the robust Universal Optimal codon Code that allows for variation but also buffers against the effects of mutation.