Cell surface receptor for Reelin (RELN) and apolipoprotein E (apoE)-containing ligands (PubMed:20223215). LRP8 participates in transmitting the extracellular Reelin signal to intracellular signaling processes, by binding to DAB1 on its cytoplasmic tail. Reelin acts via both the VLDL receptor (VLDLR) and LRP8 to regulate DAB1 tyrosine phosphorylation and microtubule function in neurons. LRP8 has higher affinity for Reelin than VLDLR. LRP8 is thus a key component of the Reelin pathway which governs neuronal layering of the forebrain during embryonic brain development. Binds the endoplasmic reticulum resident receptor-associated protein (RAP). Binds dimers of beta 2-glycoprotein I and may be involved in the suppression of platelet aggregation in the vasculature. Highly expressed in the initial segment of the epididymis, where it affects the functional expression of clusterin and phospholipid hydroperoxide glutathione peroxidase (PHGPx), two proteins required for sperm maturation. May also function as an endocytic receptor. Not required for endocytic uptake of SEPP1 in the kidney which is mediated by LRP2 (By similarity). Together with its ligand, apolipoprotein E (apoE), may indirectly play a role in the suppression of the innate immune response by controlling the survival of myeloid-derived suppressor cells (By similarity). (Microbial infection) Acts as a receptor for Semliki Forest virus. Homooligomer (PubMed:30873003). Interacts with VLDLR (PubMed:30873003). Reelin associates with two or more receptor molecules (PubMed:20223215). Interacts with DAB1 and JNK-interacting proteins. Interacts with SNX17 (By similarity). Interacts with PCSK9. Interacts with MDK; this interaction is calcium dependent (By similarity). Interacts with CLU (PubMed:24381170). (Microbial infection) Interacts with Semliki Forest virus E2-E1 heterodimer; this interaction mediates viral entry to host cell. Isoforms that contain the exon coding for a furin-type cleavage site are proteolytically processed, leading to a secreted receptor fragment. Additional isoforms seem to exist. No differences were observed in the pattern splicing between control and Alzheimer brains. Expressed mainly in brain and placenta. Also expressed in platelets and megakaryocytic cells. Not expressed in the liver. The cytoplasmic domain is involved in the binding of DAB1 and in the recruitment of JNK-interacting proteins. Isoforms, which lack part of the cytoplasmic domain, are unable to recruit members of the family of JNK interacting proteins (JIP) to the cytoplasmic tail (By similarity). O-glycosylated. Some alternatively spliced isoforms lack the O-linked sugar domain (By similarity). Undergoes sequential, furin and gamma-secretase dependent, proteolytic processing, resulting in the extracellular release of the entire ligand-binding domain as a soluble polypeptide and in the intracellular domain (ICD) release into the cytoplasm. The gamma-secretase-dependent proteolytical processing occurs after the bulk of the extracellular domain has been shed, in a furin-dependent manner, in alternatively spliced isoforms carrying the furin cleavage site. Hypoglycosylation (mainly hypo-O-glycosylation) leads to increased extracellular cleavage, which in turn results in accelerating release of the intracellular domain (ICD) by the gamma-secretase. The resulting receptor fragment is able to inhibit Reelin signaling and in particular the Reelin-induced DAB1 phosphorylation (By similarity). Tyrosine phosphorylated upon apoE binding. Ubiquitinated by MYLIP leading to degradation. The disease is caused by variants affecting the gene represented in this entry. Natural isoforms of apoE (E2, E3, E4) have similar affinities for LRP8. Contains an insert in the extracellular part which carries a furin cleavage site. Belongs to the LDLR family.