CXCR2

Chemokines have been sub-divided into families on the basis of the relative position of their cysteine residues. The a- and b- families, with four cysteine residues, are the largest and best characterized. In the a-family, one amino acid separates the first two cysteine residues (CXC); in the b-family the two cysteine residues (CC) are adjacent to each other. The a-chemokines that contain the N-terminal Glu-Leu-Arg amino acid sequence (ELR-motif) are chemotactic for neutrophils (such as IL-8), while those that do not, act on lymphocytes (such as IP-10 and MIG). Examples of chemokines under the b-family category are MCP1-5 and RANTES. The chemokine lymphotactin belongs to the g-family, with only two cysteines (C), and the recently described fractalkine or neurotactin is a member of the *-family and has the first two cysteine residues separated by three amino-acids (CXXXC). Chemokines bind to specific G protein-coupled cell surface receptors on target cells. Five CXC receptors (CXCR1-5), nine CC receptors (CCR1-9) and one CXXXC receptor (CX3CR1) have been cloned to date. Expression of chemokine receptors can be restricted to some cell types (CXCR1 is expressed in neutrophils) while others (such as CCR2) are expressed in a wide variety of cells.1 Receptor expression has also been found to be constitutive (including down regulation), inducible or restricted to a cell state of activation. In addition, some chemokine receptors are also expressed in non-hematopoietic cells, such as nerve, endothelial and epithelial cells. This suggests that chemokines have other roles besides leukocyte chemotaxis. CX3CR1, for example, is highly expressed in adult brain. Chemokine receptors are linked to phospholipases through the Gi class of G proteins (inhibition by pertussis toxin). Receptor activation leads to a cascade of cellular events including generation of inositol triphosphate, calcium release and activation of protein kinase C. Chemokine receptors also activate small GTP-binding proteins of the Ras and Rho families, the latter being involved in cell motility events. In addition, chemokines bind to non-signaling molecules such as the Duffy antigen receptor for chemokines (DARC) which may act to remove chemokines from the circulation, and heparan sulfates proteoglycans which may serve to establish an ECM concentration gradient. CXCR-1 (IL-8RA, or type I IL-8 receptor) and CXCR-2 (IL-8RB, or type II IL-8 receptor) have been shown to share approximately 77% amino acid sequence identity. IL-8 binds to both receptors with high affinity and induces rapid elevation of cytosolic Ca2+ levels. Whereas CXCR-1 is highly specific for IL-8, CXCR-2 has broad specificity and has been shown to bind with high-affinity to other ELR motif containing a chemokines including GRO, GRO (NAP-2 and ENA-78. In contrast, PF4 and IP-10 (two chemokines that lack the ELR motif) have been shown to lack binding affinity for CXCR-2. CXCR-1 and CXCR-2 are expressed by neutrophils but not B lymphocytes or T lymphocytes. Cellular Localization: Integral membrane protein. Applications: Suitable for use in Flow Cytometry. Other applications not tested. Recommended Dilution: Optimal dilutions to be determined by the researcher. Storage and Stability: May be stored at 4 degrees C for short-term only. For long-term storage and to avoid repeated freezing and thawing, aliquot Store at -20 degrees C. Aliquots are stable for at least 12 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.