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16 Cards in this Set

  • Front
  • Back
how do newly synthesized proteins fold
chaperones help some
Hsp70 chaperones bind to hydrophobic parts of polypeptides
ecoli GroES-GroEL is an Hsp60 chaperone
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
structure/function of GroEL-GroES complex
space filling, central cavity
how are proteins processed following translation
100's of diff postranslational aa modifications are glycoylation and phosphorylation
proteolytic cleavage is most common form of processing
how do proteins find their proper place in the cell
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
more protein placing in the cell
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
general features of the N-terminal in e.coli
basic region
hydrophobic residues
nonhelical C-terminal
synthesis of a euk secretory protein and its translocation into the ER 1-3
SRP recognizes signal sequence
RNS-SRP interacts with SR and transfers it to translocon
release SRP,stimulates translation
synthesis of a euk secretory protein and its translocation in the ER 4-5
signal peptidase clips off the N-terminal signal sequence
dissociation of ribo, BiP plugs translocon channel
structure of an amphipathic a-helix
basic(+) residues on one side and uncharged(-) hydrophobic residues on the other (R)
translocation of mito preproteins with distinct translocons
interact with outer mito mem
passed to SAM complex
integral mem prot or inner mito mem prot
how does protein degradation regulate cellular levels of specific proteins
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
enzymatic rxns in the ligation of ubiquitin to proteins
ubiquitin is attached to selected prot by isopeptide bonds formed bw ubiquitin carboxyterminus and free aa groups.
proteins with acidic N-terminal show a tRNA requirement for degradation
Arg-tRNA:prtein transferase catalyzed the transfer of Arg to free a-NH2. transferase also serves as part of prot degradation recognition system
structure of the 26S proteasome
(thermoplasma acidophilum)
20S proteasome core
composite is 26S proteasome
ubiquitin-proteasome degradation pathway
"lollipop":ubiquitin molecules