Sandbox Reserved 595: Difference between revisions

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ApoE exhibits extensive domain interactions. Hydrogen bonds and salt-bridges act to shield the major LDLR-binding region. This protein's unique topology regulates its tertiary structure in order to solely permit one conformation upon binding in a two-step manner. Lipid-free and partially lipidated ApoE are thwarted from prematurely binding to ApoE receptors by the tertiary structure. Therefore, the optimal receptor-binding affinity of fully lipidated ApoE is guaranteed. An active conformation for biding to members of the low-density lipoprotein receptor family is achieved through binding to lipids and HSPGs (V).

As was aforementioned, ApoE interacts with multiple partners, including LDLRs, cell-surface HSPGs, ATP-binding cassette protein 1 (ABCA1), and low-density lipoprotein-related proteins (LRPs). It binds with lipids and cholesterol, with high-affinity, to form lipoprotein particles (W). In vivo, ApoE is almost always associated with lipids and cholesterol. Concentrations of lipid-free ApoE are expected to be insignificant (M).

==Quartenary Structural Features==

ApoE proteins self-associate in order to form dimers, tetrameters, and higher aggregates. These phenomena occur in a concentration, pH, and temperature-dependent manner (N). Oligomerization also correlates with the length of the C-terminal domain (O). Resulting from this protein's propensity to aggregate is difficulty in determining the full-length three-dimensional structure (P). At μM concentrations, ApoE primarily exists as a tetrameter. When members of a tetrameter dissociate, the subsequent dimeric and monomeric forms retain their structure; dissociation from a tetrameter may serve to open new ligand binding sites (Q).

Sandbox Reserved 595: Difference between revisions

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 ApoE exhibits extensive domain interactions.  Hydrogen bonds and salt-bridges act to shield the major LDLR-binding region.  This protein's unique topology regulates its tertiary structure in order to solely permit one conformation upon binding in a two-step manner.  Lipid-free and partially lipidated ApoE are thwarted from prematurely binding to ApoE receptors by the tertiary structure.  Therefore, the optimal receptor-binding affinity of fully lipidated ApoE is guaranteed.  An active conformation for  biding to members of the low-density lipoprotein receptor family is achieved through binding to lipids and HSPGs (V).
+As was aforementioned, ApoE interacts with multiple partners, including LDLRs, cell-surface HSPGs, ATP-binding cassette protein 1 (ABCA1), and low-density lipoprotein-related proteins (LRPs).  It binds with lipids and cholesterol, with high-affinity, to form lipoprotein particles (W).  In vivo, ApoE is almost always associated with lipids and cholesterol.  Concentrations of lipid-free ApoE are expected to be insignificant (M).
+==Quartenary Structural Features==
+ApoE proteins self-associate in order to form dimers, tetrameters, and higher aggregates.  These phenomena occur in a concentration, pH, and temperature-dependent manner (N).  Oligomerization also correlates with the length of the C-terminal domain (O).  Resulting from this protein's propensity to aggregate is difficulty in determining the full-length three-dimensional structure (P).  At μM concentrations, ApoE primarily exists as a tetrameter.  When members of a tetrameter dissociate, the subsequent dimeric and monomeric forms retain their structure; dissociation from a tetrameter may serve to open new ligand binding sites (Q).