Endoplasmic reticulum

Endoplasmic reticulum

1. Eukaryotic cells

2. 2 types

   • Smooth
     • Lipid synthesis
   • Wrinkled
     • Protein synthesis
       • Cell exterior
         • Interior of other organells in the vesicular path

3. Resident proteins

   • Disulfide isomerase
     • Oxidation of sulhydril groups
   • BiP
     • Recognizes incorrectly folded proteins

4. Signal hypotesis

   • Free ribosomal subunits bind to mRNA that binds to the translocator it uses a cleavage signal.

5. Captures proteins from the cytosol

   • Transmembrane
     • Plasma membrane, organelles
   • Water soluble
     • In the lumen or an organelle for secretion

6. Signal recognition particle

   • Er signal sequence guided to the ER membrane
     • Receptor in the membrane
     • SRP moves the signal sequence to the translocon, the protein enters
   • Vary in a sequence
     • Non polar

7. Traslation

   • Ribosomes (site P and A). Iniciation: Codons iniciate (AUG) Arnt: Anticodon elongation. Termination: ribosome dissociates and protein is released

8. Chaperons

   • Help to check the folding of the protein
     • Calnexin and Calreticulum
       • They require calcium

9. Oligosaccharides used as tags to mark the state of folding