ANAT 212 Lecture Notes - Ammonia, Sec61, Signal Peptide
5 Feb 2013
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Signal peptide: hydrophobic central region (6 aa) with short polar sides. Mostly, at n-terminus, cleaved off after translocation, shorter hydrophobic signal recognition (where? how?) Srp binds signal sequence and ribosome during translocation. Ribosomes transfers frin srp-sr complex to the translocon, gtp hydrolysis by srp & sr , dissociate and recycle them, translation translocated into er lumen, energy of peptidyl-transferase (sec61 translocon-when no protein inactive and plugged, open laterally) Signal sequence in different place, another hydrophobic become tm helice, longer hydrophobic region. C-terminal (in lumen) type 2 tm , n- terminus in cytsol. Tm comes from ribosome and dissociates from it. Bat3 transfer tm sequence to trc40 targeting complex, atp bounds state with polypeptide docks onto. Tm proteins have exit signals on cytosolic side. Adaptors acts as gap, that allows sar1 to hydrolyze gtp, Sar-gdp release from vessicle membrane, adaptors separate from sar1 and coat separate from adaptors. Kdel-coo- at c-terminus recognized by tm kdel receptor with kkxx motif.
