The function of ENSG00000166856 (ACKR5, atypical chemokine receptor 5) is as follows. Atypical chemokine receptor that regulates chemokine levels and localization through chemokine binding, independently of activating classical ligand-induced signaling pathways such as G protein activation and Ca(2+) mobilization (PubMed:33875597, PubMed:35013216, PubMed:37554323, PubMed:38026988). Instead, it mediates chemokine sequestration, transport, or internalization to control their availability (PubMed:33875597, PubMed:35013216, PubMed:37554323, PubMed:38026988). Acts as a scavenger for a broad range of chemokines from CXC, CC and XC chemokine ligand families including CXCL9, CXCL10, CXCL12, CXCL13, CXCL11, CXCL14, CCL1, CCL11, CCL19, CCL25, CCL28 and XCL1 (PubMed:33875597, PubMed:35013216, PubMed:38026988). Is the only atypical receptor for chemokines CXCL13 and CCL28 (PubMed:37554323). Has a strong constitutive association with beta-arrestins, which is essential for intracellular receptor trafficking and chemokine scavenging, and occurs independently of ligand binding (PubMed:33875597, PubMed:37554323). Cooperates with ACKR3 and ACKR4 in regulating serum levels of CXCL12 and CCL19, respectively (PubMed:37554323). Acts as an important modulator of cellular immunity (By similarity). {ECO:0000250|UniProtKB:P43142, ECO:0000269|PubMed:33875597, ECO:0000269|PubMed:35013216, ECO:0000269|PubMed:37554323, ECO:0000269|PubMed:38026988}.