Sandbox Reserved 595: Difference between revisions
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The carboxyl-terminal domain is 10kD respectively, and consists of the residues 216-299 (C,F). It presents a large exposed hydrophobic surface that is well-suited for interacting with multiple binding partners, including lipids, heparin sulfate proteoglycans (HSPGs), and amyloid beta peptides (Aβ) (V). This domain harbors high-affinity lipid binding properties and is therefore capable of anchoring lipoprotein particles; it also contains sites that mediate ApoE self-association (C,D,I,J,P). The C-terminal domain includes two kinds of amphipathic alpha helices. The first of these alpha helices is a class A helix (residues 216-266) and the second is a class G helix (residues 273-299) (D). Residues 230-270 in the C-terminal domain are crucial for oligomer formation(M). Those residues that are important for the initiation of lipid binding to ApoE are 261-272 (M). | The carboxyl-terminal domain is 10kD respectively, and consists of the residues 216-299 (C,F). It presents a large exposed hydrophobic surface that is well-suited for interacting with multiple binding partners, including lipids, heparin sulfate proteoglycans (HSPGs), and amyloid beta peptides (Aβ) (V). This domain harbors high-affinity lipid binding properties and is therefore capable of anchoring lipoprotein particles; it also contains sites that mediate ApoE self-association (C,D,I,J,P). The C-terminal domain includes two kinds of amphipathic alpha helices. The first of these alpha helices is a class A helix (residues 216-266) and the second is a class G helix (residues 273-299) (D). Residues 230-270 in the C-terminal domain are crucial for oligomer formation(M). Those residues that are important for the initiation of lipid binding to ApoE are 261-272 (M). | ||
Connecting the N-terminal and C-terminal domains is the flexible hinge region, which extends approximately from residue 165 to residue 215 (B,H). This region is protease sensitive (M). | |||
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). | |||