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16 Cards in this Set
- Front
- Back
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how do newly synthesized proteins fold
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chaperones help some
Hsp70 chaperones bind to hydrophobic parts of polypeptides ecoli GroES-GroEL is an Hsp60 chaperone |
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structure and function of DnaK
mechanism of action |
N-terminal:ATP binding
DnaJ binds an unfolded protein U or partially folded intermediate and delivers it to DnaK |
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structure/function of GroEL-GroES complex
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space filling, central cavity
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how are proteins processed following translation
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100's of diff postranslational aa modifications are glycoylation and phosphorylation
proteolytic cleavage is most common form of processing |
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how do proteins find their proper place in the cell
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proteins are delivered to cell compartment by translocation
prok proteins for translocation are made as preproteins with amino terminal leader sequences euk proteins routed thru sorting and translocation |
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more protein placing in the cell
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synthesis of secretory and mem proteins is coupled to translocation across the ER mem
singal recog particles (SRP), SR's and translocons together do secretory protein translocation mito have specific translocons for their outer and inner mems |
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general features of the N-terminal in e.coli
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basic region
hydrophobic residues nonhelical C-terminal |
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synthesis of a euk secretory protein and its translocation into the ER 1-3
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SRP recognizes signal sequence
RNS-SRP interacts with SR and transfers it to translocon release SRP,stimulates translation |
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synthesis of a euk secretory protein and its translocation in the ER 4-5
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signal peptidase clips off the N-terminal signal sequence
dissociation of ribo, BiP plugs translocon channel |
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structure of an amphipathic a-helix
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basic(+) residues on one side and uncharged(-) hydrophobic residues on the other (R)
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translocation of mito preproteins with distinct translocons
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interact with outer mito mem
passed to SAM complex integral mem prot or inner mito mem prot |
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how does protein degradation regulate cellular levels of specific proteins
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euk prot are degraded by lysosomes or proteasomes
euk prot targeted for proteasome destruction by ubiquitination proteasome core is a7b7b7a7 cap on the ends of proteasomes select ubiquitinated proteins for degradtion in the core activity |
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enzymatic rxns in the ligation of ubiquitin to proteins
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ubiquitin is attached to selected prot by isopeptide bonds formed bw ubiquitin carboxyterminus and free aa groups.
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proteins with acidic N-terminal show a tRNA requirement for degradation
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Arg-tRNA:prtein transferase catalyzed the transfer of Arg to free a-NH2. transferase also serves as part of prot degradation recognition system
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structure of the 26S proteasome
(thermoplasma acidophilum) |
20S proteasome core
composite is 26S proteasome |
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ubiquitin-proteasome degradation pathway
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"lollipop":ubiquitin molecules
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