Protein and structure
- Created by: Alice Fisher
- Created on: 06-05-15 20:34
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- 8 Protein Structure and Function
- Different mechanisms of protein self assembly
- Assembly on core, accumulated stain, vernier mechanism
- e.g. viral capsizes self assemble from identical monomers, tobacco mosaic virus (TMV) assembles around an RNA core
- Interactions require complementary surfaces
- 1) Surface - string, 2) Surface - surface 3) Helix - helix
- Further interactions
- Hydrophobic interactions drive coiled-coil packaging
- Tubulin subunits that make up microtubules can pack into a variety of structures; filaments, sheets, rings, tubes
- Lipid membrane hydrophobic and so must proteins that cross it
- Single pass, multiples, B-barrel (pore), amphipathic helix
- Hydropathy plots can show which parts of transmembrane proteins are hydrophobic
- Lipid modifications
- A variety of lipophilic covalent attachementsthat help to bind proteins to membranes
- Inside; acylation or prenylation
- Outside; GPI anchors (a simple sugar and a phospholipid)
- A variety of lipophilic covalent attachementsthat help to bind proteins to membranes
- Carbohydrate modification (glycosylation)
- Modification of extra-cellular proteins
- Two types; N linked (attached via asparagine) or o-linked (attached via hydroxyl group of serine, threonine or hydroxycysteine
- Gives cellular protection; mucins in mucous
- Provides adhesive properties; sticky
- Provides a varied and complex set of surfaces for interactions
- Phosphorylation and dephospho rylation
- Majour secondary and regulatory modification. No intrinsic.
- Protein kinases (Src) - acts as a switch. Converts a hydroxyl group to a bulky charged phosphate group.
- Proteins as molecular motors
- ATP dependent movement along a track. (Myosin in actin, kinesin in microtubules,polymerases on DNA)
- Different mechanisms of protein self assembly
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