BIOB10H3 Lecture 4: BIOB10 Lecture 4.docx
15 Apr 2012
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Electron microscopes: don"t see where individ protiens are. Cell or tissue must be dead and section them. Cytosol: all the fluid and proteins that bathe the cell, between the organelles. Plasma membrane proteins: adhesion molecules (that stick to ecm or other cells), Resident er and golgi proteins: translocon, srp receptor and kdel receptor. All proteins start at the er (endoplasmic reticulum) How does cell know to target a protein to er: for all proteins, they have a special amino acid sequence (signal sequence, very specific amino acid sequence that"s at the beginning of the protein). A protein complex called srp goes and binds to the signal sequence. The srp has high affinity for srp receptor, which is on the er. Srp binds to the receptor on the er. Next to the srp is the translocon (series of proteins that form a pore). The signal sequence binds to srp, and then translation temporarily stops till you get to the er.
