Lectures 6 7 - Proteinfolding and Chaperones

Recognizes exposed hb patches prevent aggregation of

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– Recognizes exposed HB patches – Prevent aggregation of unfolded or misfolded proteins • HSP70 – Assembly & disassembly of oligomers – Regulate translocation to ER HSP60 (GroEL) & HSP10 (GroES) – Work as a complex
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Each subunit Apical (  motif) Opening of chaperone to unfolded protein • Flexible • HB Intermediate ( helices) Allow ATP and ADP diffusion Flexible hinges Equatorial ( helices) ATP binding site Stabilizes double ring structure Central cavity up to 90Å diam. 7 subunits in one ring 2 rings back to back GroEL
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Cap to the GroEL Each subunit sheet hairpin (roof) Mobile loop (int w/ GroEL) 7 subunits in functional molecule GroES
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GroEL+ GroES work together GroEL makes up a cylinder Each side has 7 identical subunits Each side can accommodate one unfolded protein 1 GroES binds to one side of GroEL at a time Allosteric inhibition at other site One side of cylinder is actively folding protein at a time
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1.GroEL/ATP complex at side A 2.Bind GroES on this side 7 ATP 7 ADP this side has a wider cavity but closed top other side has smaller cavity and open top 3.Side B ring binds unfolded protein GroES falls off of side A ADP falls off of side A 4.Side B ring binds 7 ATPs 5.GroES binds GroEL/ATP 7 ATP 7 ADP protein folding occurs 6.Side A ring binds 7 ATPs protein folding occurs 7 ATP 7 ADP (side A) 7 ADP & GroES (side B) falls off 7.Side A ring binds next unfolded protein
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