Ith a single web site on the murine IL-8 IL-8 receptor homologue. Their chemokine activity on human neureceptor (Bozic etal., 1995). The molecular identityof the second trophils, however, is unique. MIP-2 is chemotactic for human Bak review binding web-site KC on murine neutrophils remains determined. for to be Human neutrophils express IL-8 receptors. Equilibrium bind- neutrophils, whereas KC doesn’t induce the migration of human two neutrophils in spite of the high affinity binding for the IL-8 kind B ing experiments with steady cell lines expressingeachreceptor receptor (Bozic et al, 1994). . indicate that “-2 has high affinity for the kind B receptor, butCharacterization of MIP-2 Receptor binding epitopesextended amino terminus that interferes with receptor binding (Walz et al., 1989; Moser etal., 1991). Hybrid proteins between IL-8 and the a-chemokines PF-4 or IP-10, two proteins that usually do not bind neutrophils, underscore the importance from the N-terminal surface in receptor binding. A single IL-8/IP-10 hybrid containing all of the identical residues on the N-terminal surface possesses the potency and neutrophil binding properties of wild-type IL-8 (Clark-Lewis et al., 1994). The IL-8/PF-4 hybrid protein with greatest neutrophil activity displays 1/15th the affinity of IL-8 for neutrophils (ClarkLewis et ai., 1993). This hybrid protein features a leucine as opposed to a proline at position 53,suggesting that a subtle transform in the N-terminal surface can compromise binding to neutrophils. A similar sort of sequence evaluation to recognize residues that impart specificity for binding to the IL-8 form A receptor just isn’t doable since IL-8 may be the only chemokine with high-affinity binding to this receptor. Having said that, an analysis of variations among IL-8 and also the five other chemokines reveals a cluster of hydrophobic and aromatic residues present in IL-8,but not in the other chemokines. This hydrophobic surface is surrounded by several residues that exhibit charge LTB4 Accession differences with corresponding residues in the other chemokines. The distribution of hydrophobic and charged residues at this region with the structure is likely to market binding of IL-8 to the kind A IL-8 receptor and preclude the other chemokines from binding to this receptor. The results of this analysis are constant with recent experiments to recognize critical residues for binding towards the IL-8 kind A receptor. Tyr-13 and Lys-15 had been shown to impart IL-8 sort A receptor binding to rabbit IL-8 (Scraufstatter et al., 1995). A groy/IL-8 chimeric chemokine possessing IL-8 residues 1-18 and 46-53 confers high-affinity binding to both IL-8 receptors (Hammond et al., 1996). The area consisting of residues 18-32 but not 32-46 was also identified to be involved in binding to both receptors. In a related experiment involving gro-a/IL-8 chimeric chemokines, IL-8 residues 10, 11, 13-17, and 49 imparted IL-8 form A receptor binding properties to gro-a(Lowman et al., 1996). Phe-21 was also found to improve binding to this receptor. An NMR study identifies a a great deal larger number of residues (including Gln-8, Thr12, Lys-15, Phe-17, His-18, Lys-20, Phe-21, Ser-44, Gln-48, Leu49, Cys-50, and Val-61) that interact having a peptide corresponding towards the amino terminus in the kind A IL-8 receptor (Clubb et al., 1994) . The present sequence evaluation and mutagenesis study supports a vital part for the N-terminus of a-chemokines and suggests that the receptor binding region is a great deal bigger than anticipated previously primarily based solely on.
