Recombinant Cotton Rat GRO Protein

Cotton rat growth-regulated protein (GRO) is a member of the ELR⁺ CXC subfamily of chemokines (1). The cotton rat GRO cDNA encodes a 100 amino acid (aa) residue precursor protein with a 27 aa putative signal peptide and a 73 aa mature protein (2). Among the three human GRO proteins, mature cotton rat GRO is most closely related to GRO alpha/CXCL1, sharing approximately 77% aa sequence identity (3). It also shares 75% and 70% aa sequence identity with mature human GRO beta/CXCL2 and GRO gamma/CXCL3, respectively (4). Compared with rat CXC chemokines, mature cotton rat shows 92%, 76%, and 76% aa sequence homology with rat KC/GRO/CINC-1, CINC-2 and CINC-3, respectively (5). Mature cotton rat GRO also shares 74% sequence homology with mature cotton rat MIP-2 (6). Similarly to GRO proteins from other species, cotton rat GRO is expected to be a potent neutrophil chemoattractant and activator. Cotton rat GRO has been shown to bind and activate both mouse chemokine receptors CXCR1 and CXCR2 (7). Similarly to human GRO alpha, the cotton rat GRO concentration required to activate CXCR1 is at least an order of magnitude higher than that required to activate CXCR2 (7, 8). Based on studies on rodents, cotton rat GRO is predicted to be produced by a wide variety of cell types including macrophages, endothelial cells, fibroblasts, astrocytes, neutrophils, keratinocytes and intestinal epithelium (1, 9).