BIOC12H3 Lecture Notes - Lecture 6: Steroid Hormone Receptor, Superoxide Dismutase, Golgi Apparatus
21 Jul 2013
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Document Summary
Identical polypeptide chains are called protomers, also known as (aka) multiple monomers. Subunits are held together by weak non-covalent bonds, primarily hydrophobic. Tight association provides stable structure, but the interaction cannot be too strong to allow separation of subunits. Quaternary (4 ) structure is more stable than individual subunit or tertiary (3) structure, regardless if the individual subunit has same or different polypeptide chains as the 4 structure. 4 structure has a greater half life because it is more stable. Interior (inside) of a single subunit is hydrophobic, folds to the center (core) Contact regions (interactive area between different subunits) are also hydrophobic. In some cases, one subunit does not contain the substrate binding site. Different proteins can share same subunits, meaning they have identical subunits that allow the same ligand to bind. Ex. if j binds to a & b subunits and also c & d subunits, the identity of j is a ligand.
