ANAT 212 Lecture Notes - Lecture 4: Hsf1, Groel, Peptide
30 Mar 2020
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Document Summary
From lecture 3: we saw 3 families of atp-dependent chaperones: hsp70, hsp90 and the chaperonins. Each of them have their own atpase cycle where atp binding and hydrolysis controls the binding and release of substrate polypeptide. From lecture 2: stress response and how the heat shock response in the cytosol is controlled by the transcription factor hsf1 and the chaperone hsp90. A drug prevents hsp90 from binding polypeptide substrates. Under non-stress conditions, hsf1 is in equilibrium between the inactive monomer and the active trimer. When it is in the inactive monomer, it can be bound by hsp90 and when there is a lot of unfolded polypeptide in the cell than, hsp90 will prefer to bind to the unfolded polypeptide which will release. Hsf1 to trimerize and that will induce the expression of more chaperones including hsp90. When there is an excess of hsp90, then we get rid of the unfolded proteins and now, it can bind the inactive monomer.
