Mechanism of targeting proteins to ER

Mechanism of targeting proteins to ER - 3. o receptor...

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Mechanism of targeting proteins to ER : (Fig. 9.7) Signal sequence (~20 AA) usually at amino terminus of polypeptide ------ first part to emerge from ribosome 1. while emerging, signal sequence is specifically recognized and bound by signal recognition particle ( SRP ) which consists, next to polypeptides, of a small cytosolic or scRNA . Binding inhibits further translation 2. complex binds to SRP receptor on ER membrane ----- targeting
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Unformatted text preview: 3. o receptor releases free SRP o ribosome binds to protein translocation complex localized in ER membrane o signal sequence is inserted into membrane channel of protein translocation complex 4. translation is resumed with polypeptide growing through channel, during translocation (growth through channel) signal sequence is cleaved by signal peptidase 5. complete polypeptide released into ER lumen...
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