GroEL belongs to the chaperonin family of molecular chaperones, and is found in a large number of bacteria. It is required for the proper folding of many proteins. To function properly, GroEL requires the lid-like cochaperonin protein complex GroES. In eukaryotes the proteins Hsp60 and Hsp10 are structurally and functionally nearly identical to GroEL and GroES, respectively.
Within the cell, the process of GroEL/ES mediated protein folding involves multiple rounds of binding, encapsulation, and release of substrate protein. Unfolded substrate proteins bind to a hydrophobic binding patch on the interior rim of the open cavity of GroEL, forming a binary complex with the chaperonin. Binding of substrate protein in this manner, in addition to binding of ATP, induces a conformational change that allows association of the binary complex with a separate lid structure, GroES. Binding of GroES to the open cavity of the chaperonin induces the individual subunits of the chaperonin to rotate such that the hydrophobic substrate binding site is removed from the interior of the cavity, causing the substrate protein to be ejected from the rim into the now largely hydrophilic chamber. The hydrophilic environment of the chamber favors the burying of hydrophobic residues of the substrate, inducing substrate folding. Hydrolysis of ATP and binding of a new substrate protein to the opposite cavity sends an allosteric signal causing GroES and the encapsulated protein to be released into the cytosol. A given protein will undergo multiple rounds of folding, returning each time to its original unfolded state, until the native conformation or an intermediate structure committed to reaching the native state is achieved. Alternatively, the substrate may succumb to a competing reaction, such as misfolding and aggregation with other misfolded proteins.
Lying alone in this cold and quiet room
I can hear their whispers now
I can sense it: A turn is coming on
Lying alone in this cold and quiet room
The door is silently opening
I can sense it: A turn is coming on
Wincing faces, racked by pain
They come to me as I fall asleep
Climbing the stairs, to hide is vain
They will get me in this night so deep
Exhausted veins
Bloody drugs every day
Their needles in my brain
They gave me one more jab supposed to relieve all that pain
I tried to get away
To escape from that place
But my own legs betray me leaving body on that bed
Wincing faces, in front of me
They've come to me and I don't dare
To give that fight for eternity