Interpretation:
Interactions in LDL receptor should be identified.
Concept Introduction:
LDL receptor has five domains. N terminal LDL binding domain contains seven cysteine rich repeats referred as R1 to R7. Next epidermal growth factor repeats and ß propeller module can be found. Those segments are followed by O-linked oligosaccharide, a membrane spanning segment and another segment extended towards the cytosol. LDL particles bind with R4 and R5 cysteine repeats. At low pH, the LDL receptor polypeptide folds so that ß propeller domain is associated with R4 and R5 displacing the LDL particle. These two repeats contain two loops connected by 3 disulfide bonds. Second loop of each repeat have Asp and Glu acidic residues and acts as a Ca2+ binding site.
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Biochemistry
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