Biology 2382B Lecture Notes - Integral Membrane Protein, Transmembrane Domain, Lipid Bilayer
14 Apr 2014
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Document Summary
Membrane proteins: with the exception of needing phospholipids to form semi- permeable closed compartments, membrane proteins carry out the biological functions of membranes. Three distinct domains : cytoplasmic (hydrophilic, transmembrane (hydrophobic, exoplasmic (hydrophilic) Transmembrane domain hydrophobic secondary or tertiary structures that span the lipid bilayer: different configurations most common are the helices and barrels, helices (approx. 20-25 amino acids: mostly glycosylated in exoplasmic domain (extracellular area) Arg and lys (charged aas) near cytosolic side interact with polar head groups. Proteins that are linked to existing phospholipids in the bilayer. Proteins anchored to membrane by lipophilic adduct: acylation of gly residue of protein. Need n-terminal glycine: prenylation of cys residue of protein. Need c-terminal cysteine or cysteine close to c-terminal. Linked to cytosolic side of the membrane: glycosylphosphatidylinositol (gpi) anchor. With phosphatidylinositol, certain proteins can be linked. Recall: n-cam is integral membrane protein has all three domains and is involved in cell adhesion.
