BIOL 2021 Lecture Notes - Lecture 7: Sec61, Transmembrane Protein, Membrane Protein
9 Feb 2018
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Fig 12-32 co-translational and post-translational import: mammalian cells begin to import most proteins into the er before complete synthesis of the polypeptide chain that is, import is a co-translational process. Don"t get translocated all the way inside the lumen. Most proteins use co- translational: nuclei, mitos and chloros: post-translational, note: some proteins imported into er post-translationally: method similar to mitos. Important video (watch video and write down): er is the most extensive membrane system. Video 12. 5: protein translocation, co-translational import of soluble proteins. Fig 12-37 signal sequences and srp: ribosomes start translating mrna, signal sequence is made first, signal sequence = start-transfer sequence, signal-recognition particle binds to signal sequence, translation pauses. Until you get down to membrane to find available translocators: srp binds to srp receptors in membrane, the srp and its receptor act in concert. The srp binds to both the exposed er signal sequence and the ribosome, thereby inducing a pause in translation.
