Plasma membrane 8.1Introduction y00me■G0g Mannose-6-phosphate C-terminal KDEL Figure 8.3 Membrane-bound ribosomes have proteins with N-terminal sequences N-teminal signal that enter the er during sequence is cleaved synthesis. The proteins may Endoplasmic reticulum flow through to the plasma membrane or may be Cytosol diverted to other destinations by specific signals 消当
Figure 8.3 Membrane-bound ribosomes have proteins with N-terminal sequences that enter the ER during synthesis. The proteins may flow through to the plasma membrane or may be diverted to other destinations by specific signals. 8.1 Introduction
8.2 Chaperones may be required Protein acquires confomation after for protein folding membrane passage Protein must pass through channel in membrane Figure 8.4 a protein is constrained to a Folded conform ation narrow passage as it could prevent passage through membrane crosses a membrane 消当
Figure 8.4 A protein is constrained to a narrow passage as it crosses a membrane. 8.2 Chaperones may be required for protein folding
8.2 Chaperones may be required for protein folding System Function HSp70 H sp70(Dnak) ATPase H sp40(DnaJ) stimulates ATPase GrpE (GrpE) Nucleotide exchange factor Chaperonin H sp60(GroEL)Foms two heptameric rings Hsp10 (GroES)Foms cap Figure 8.5 Chaperone families have eukaryotic and bacterial counterparts(named in parentheses) 消当
Figure 8.5 Chaperone families have eukaryotic and bacterial counterparts (named in parentheses). 8.2 Chaperones may be required for protein folding
8.3 The Hsp70 family is ubiquitous rpE ATP ATP→ ADP EtADP DnaJ DnaK 甲■ ycle is repeated Figure 8.6 Dnaj assists the binding of Dnak(hsp70), which assists the folding of nascent proteins. ATP hydrolysis drives conformational change. Grpe displaces the ADP this causes the chaperones to be released. Multiple cycles of association and dissociation may occur during the folding of a substrate protein 消当
Figure 8.6 DnaJ assists the binding of DnaK (Hsp70), which assists the folding of nascent proteins. ATP hydrolysis drives conformational change. GrpE displaces the ADP; this causes the chaperones to be released. Multiple cycles of association and dissociation may occur during the folding of a substrate protein. 8.3 The Hsp70 family is ubiquitous
8.4 Hsp60/GroEL Pr otein enters throu gh forms an end of cylinder oligomeric ring structure Figure 8.7-IA protein may sequestered within a controlled environment for folding or Protein in tracts only degradation with walls of cavity 消当
Figure 8.7-1 A protein may be sequestered within a controlled environment for folding or degradation. 8.4 Hsp60/GroEL forms an oligomeric ring structure