CCL3L1 is one of several chemokine genes clustered on the q-arm of chromosome 17. Specifically, chemokines attract lymphocytes to sites of infection or damage. This protein binds to several chemokine receptors including chemokine binding protein 2 (CCBP2 or D6) and chemokine (C-C motif) receptor 5 (CCR5).

CCR5 is a co-receptor for HIV, and binding of CCL3L1 to CCR5 inhibits HIV entry. Furthermore, the binding causes the receptor to be taken inside the cell by endocytosis, to eventually be reprocessed and re-expressed.The human genome reference assembly contains two full copies of the gene (CCL3L1 and CCL3L3) and an additional partial duplication, which is thought to result in a pseudogene, designated CCL3L2. This record represents the more telomeric full-length gene.