Sequence similarities of a subgroup of CXC chemokines related to murine LIX: implications for the interpretation of evolutionary relationships among chemokines

The murine CXC chemokine LIX has distinctive sequence features that suggest it is a novel chemokine. Among known human chemokines, ENA‐78 and GCP‐2 are the two most closely related to LIX. We have recently cloned the human GCP‐2 gene. Phylogenetic analysis shows that the LIX coding region is more distant from both human GCP‐2 and ENA‐78 than is porcine AMCF‐II, the chemokine with greatest sequence similarity to LIX. Human GCP‐2 and ENA‐78 have very high nucleotide similarity in non‐coding as well as coding sequences, which suggests that these genes are the result of an evolutionarily recent gene duplication event. If this duplication occurred during primate evolution, then non‐primate species may have only a single chemokine corresponding to this pair of human genes. This example shows that a one‐to‐one genetic correspondence does not necessarily exist between all the chemokine genes in two different species. These observations may have important implications for other chemokines that belong to clusters of closely related genes. J. Leukoc. Biol.62: 598–603; 1997.