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Chromatin remodelling and modification ( week 9), 1 - Coggle Diagram

- - - - Proteins can move bt compartments in diff ways: gated transport, transmembrane transport, vesicular transport
        1. Gated transport: bt nucelus & cytosol
        2. Transmembrane transport: bt nucleus and organelles (ie mitochondria, endoplasmic reticulum)
        3. Vesicular transport: bt organelles (ie golgi to cell extracellular, golgi to early endosome to extracellular)
      - Signal sequencing & sorting receptors direct proteins to the correct cell address.
        Import into cells: nuclear localisation sequence (NLS), chain of Lys.
        Export from nucleus: Nuclear export (NES).
        Import into ER: signal sequence is hydrophobic.
        Protein contains a specific signals that direct their transport to particular cellular compartment. NLS guide proteins into the nucleus while other signals determine transport to the endoplasmic reticulum, Golgi apparatus or extracellular space.
      - Steps:
        
        Signal sequence of growing peptide is recognised by SRP to signal peptide causes a pause in translation.
        
        Translation continues and translocation begins.
        
        Binding of SRP to its receptor on the ER, and help the ribosome bind to the protein translocator.
        
        Dissociation of the ribosome from the SRP complex, and translation continues and translocator allows the polypeptide to transport across the ER lumen and folding occurs in the ER lumen.
        
        Signal peptidase is present in the ER responsible for cleaving inner peptide and releasing protein into the lumen.
  - - - Molecular sinals direct addition of covalent modifications. The "fate" of protein after the code is read is:
        1: Bind to proteins Y and Z
        2: Move to nucleus
        3: Move to proteasome for degradation
        4: Move to plasma membrane
    - - Important for activation of digestive enzymes, blood group antigens and receptors, kinase substrates.
        Meaning: cleavage of proteins
    - - Meaning: addition of sugars
        Occurs in the RER & involves the addition of a common oligosaccharide.
        
        Covalently attached to the side chain of an asparagine residue (N linked).
        
        May be required for folding, stability and function.
        
        Stabilised by disulfide bonds
        
        Covalent bond between 2 cysteine side chains intra or inter molecular crosslinks.
        
        Requires oxidative condition