Intracellular Staining by Flow Cytometry
|Detection of CXCL6/GCP‑2 in U937 Human Cell Line by Flow Cytometry. U937 human histiocytic lymphoma cell line was stained with Mouse Anti-Human CXCL6/GCP‑2 APC‑conjugated Monoclonal Antibody (Catalog # IC333A, filled histogram) or isotype control antibody (Catalog # IC002A, open histogram). To facilitate intracellular staining, cells were fixed with Flow Cytometry Fixation Buffer (Catalog # FC004) and permeabilized with Flow Cytometry Permeabilization/Wash Buffer I (Catalog # FC005). View our protocol for Staining Intracellular Molecules.|
GCP-2 (Granulocyte Chemotactic Protein-2) also known as CXCL6, is a 6-8 kDa CXC chemokine initially isolated as a neutrophil chemoattractant from the MG-63 osteosarcoma cell line. Among human CXC chemokines, GCP-2 is most closely related to ENA-78 (78% amino acid (aa) sequence identity in the mature peptide region). The structure and sequence of the genes for human GCP-2 and ENA-78 exhibit close similarity suggesting the two genes may have originated from a gene duplication. In mouse LIX (LPS-Induced CXC chemokine) was initially cloned as a gene induced by LPS in fibroblasts. The predicted LIX protein sequence is identical to a previously purified mouse protein designated mouse GCP-2 based on its amino sequence similarity (60% sequence identity) to human GCP-2. In general, however, LIX and human GCP-2 are considered orthologs.
Human GCP-2 cDNA encodes a propeptide of 114 amino acid residues with a predicted 37 aa residue signal peptide and 77 aa residue mature protein. Several forms of natural GCP-2 have been isolated from MG-63 conditioned media, indicating that GCP-2 undergoes considerable processing at both the N- and C-termini. GCP-2 is secreted as a homodimer.
Human GCP-2 has been shown to chemoattract and activate neutrophils, but not eosinophils and monocytes. It is secreted by macrophages and select epithelium. It is likely that GCP-2 activities on cells are mediated via both CXCR1 and CXCR2. By contrast, GCP-2 is known to act on bacteria as an act on bacteria as an antimicrobial.