Binds LDL, the major cholesterol-carrying lipoprotein of plasma, and transports it into cells by endocytosis. In order to be internalized, the receptor-ligand complexes must first cluster into clathrin-coated pits. Interacts (via NPXY motif) with DAB2 (via PID domain); the interaction is impaired by tyrosine phosphorylation of the NPXY motif (PubMed:11247302). Interacts (via NPXY motif) with LDLRAP1 (via PID domain) (By similarity). Interacts with ARRB1 (By similarity). Interacts with SNX17 (PubMed:12169628). Interacts with the full-length immature form of PCSK9 (via C-terminus) (By similarity). Rapidly endocytosed upon ligand binding. The NPXY motif mediates the interaction with the clathrin adapter DAB2 and with LDLRAP1 which are involved in receptor internalization. A few residues outside the motif also play a role in the interaction. N- and O-glycosylated. Ubiquitinated by MYLIP leading to degradation. Belongs to the LDLR family.