Atypical chemokine receptor that controls chemokine levels and localization via high-affinity chemokine binding that is uncoupled from classic ligand-driven signal transduction cascades, resulting instead in chemokine sequestration, degradation, or transcytosis. Also known as interceptor (internalizing receptor) or chemokine-scavenging receptor or chemokine decoy receptor. Acts as a receptor for chemokines CXCL11 and CXCL12/SDF1. Chemokine binding does not activate G-protein-mediated signal transduction but instead induces beta-arrestin recruitment, leading to ligand internalization and activation of MAPK signaling pathway. Required for regulation of CXCR4 protein levels in migrating interneurons, thereby adapting their chemokine responsiveness. In glioma cells, transduces signals via MEK/ERK pathway, mediating resistance to apoptosis. Promotes cell growth and survival. Not involved in cell migration, adhesion or proliferation of normal hematopoietic progenitors but activated by CXCL11 in malignant hemapoietic cells, leading to phosphorylation of ERK1/2 (MAPK3/MAPK1) and enhanced cell adhesion and migration. Plays a regulatory role in CXCR4-mediated activation of cell surface integrins by CXCL12. Required for heart valve development. Regulates axon guidance in the oculomotor system through the regulation of CXCL12 levels (PubMed:31211835). Homodimer. Can form heterodimers with CXCR4; heterodimerization may regulate CXCR4 signaling activity. Interacts with ARRB1 and ARRB2. Predominantly localizes to endocytic vesicles, and upon stimulation by the ligand is internalized via clathrin-coated pits in a beta-arrestin-dependent manner. Once internalized, the ligand dissociates from the receptor, and is targeted to degradation while the receptor is recycled back to the cell membrane. Not detected in blood, liver, lung and heart, but high expression detected in several tumor cell lines (at protein level). Expressed in heart, spleen, kidney, lung, ovary, brain, testis, astrocytes, neutrophils and B-lymphocytes. Expression detected after 9.5 dpc in the endothelial layer of the forming heart, neural tube, brain and septum transversum. At 10.5 dpc, expressed at high levels in the prosencephalon and in a part of the rhombencephalon and at lower levels in the neural tube, somites and heart. Detected in liver at 11 dpc and 13 dpc, but not at 15 dpc and 17 dpc. During heart development, expression detected mainly in endocardial cells and endocardial cushion mesenchymal cells in both outflow tract and atrioventricular canal regions and to a lesser degree in myocardial cells at 10.5 dpc, in the mesenchyme of the forming valves and in numerous microvessels in the myocardium at 12.5 dpc, and from 14.5 dpc onward mainly in the microvasculature associated with myocardium, valves and great vessels. In developing telencephalon, observed at 11.5 dpc in the ventral telencephalon in proliferative zones of the medial ganglionic eminence (MGE), in ventral part of the lateral ganglionic eminence (LGE) and in Cajal-Retzius (CR) neurons of dorsal telencephalon. At 12.5 dpc, detected in migrating olfactory tubercle neuron precursors and cortical interneurons, and in CR cells and subplate neurons of the cortex. At 13.5 dpc, observed in the germinal zone of MGE in the subpallium, in the marginal zone and cortical subventricular zone (SVZ) of the lateral cortex as well as in pyramidal cells and tangentially migrating interneurons. At postnatal stages, expressed in postnatal cortical plate and in migrating olfactory bulb interneurons in the striatal SVZ and rostral migratory stream. Expressed in the developing neuroepithelium in the region of the developing oculomotor nucleus at 11.5 dpc and 13.5 dpc (PubMed:31211835). The C-terminal cytoplasmic tail, plays a key role in: correct trafficking to the cell membrane, recruitment of beta-arrestin, ubiquitination, and in chemokine scavenging and signaling functions. The Ser/Thr residues and the Lys residues in the C-terminal cytoplasmic tail are essential for beta-arrestin recruitment and ubiquitination respectively. The Ser/Thr residues in the C-terminal cytoplasmic tail may be phosphorylated. Ubiquitinated at the Lys residues in its C-terminal cytoplasmic tail and is essential for correct trafficking from and to the cell membrane. Deubiquitinated by CXCL12-stimulation in a reversible manner. Lethal at perinatal stages, with most of the neonates dying within 24 hours. Mutants display slightly enlarged heart, but no clear effect on heart functionality is observed. Mutant mice display abnormalities in semilunar valves and ventricles, myocardial degeneration and fibrosis, as well as abnormal intracortical migration of interneurons and premature invasion of the cortical plate. According to PubMed:17804806, mutants display ventricular septal and atrial septal defects. According to PubMed:21246655, mutants display ventricular septal defects but no atrial septal defects. According to PubMed:18442043, no abnormalities in semilunar valve formation or ventricular septal defects are observed. No effect on hematopoiesis, neural development and gastrointestinal vascularization is observed. No apparent bone phenotype is observed. Mutant embryos show oculomotor nerve misrouting, ranging from complete misprojection in the midbrain, to aberrant peripheral branching, to a thin nerve, which aberrantly innervates the lateral rectus (PubMed:31211835). Belongs to the G-protein coupled receptor 1 family. Atypical chemokine receptor subfamily.