Granulocyte macrophage colony stimulating fact or receptor alpha (GMCSF Ralpha) , also known as CD116, is a component of the receptor complex that mediates cellular responses to GMCSF. GMCSF promotes the differentiation and mobilization of granulocytemacrophage, erythroid, megakaryocyte, and eosinophil progenitors. It enhances the activation of myeloid cell effect or functions and plays a role in the development of Th1 biased immune responses, allergic inflammation, and autoimmunity (1 4). Mature human GMCSF Ralpha is an 80kD type I transmembrane glycoprotein that consists of a 298 amino acid (aa) extracellular domain (ECD) with two fibronect in type III domains and a juxtamembrane WSXWS motif , a 26 aa transmembrane segment , and a 54 aa cytoplasmic domain (5). Within the ECD, human GMCSF Ralpha shares approximately 33% aa sequence identity with mouse and rat GMCSF Ralpha. Alternate splicing of human GMCSF Ralpha generates several additional isoforms that lack the cytoplasmic and/or transmembrane regions. Soluble forms of the receptor retain the ability to bind GMCSF ( 6, 7) . GMCSF Ralpha is expressed on hematopoieticstem cells, progenitor and differentiated cells in the myeloid lineage, vascular endothelial cells, placenta, and nonhematopoietic solid tumor cells (8). GMCSF Ralpha associates with the common beta chain/CD131 (beta c ), a135kD transmembrane protein that is also the signal transducing component of the receptors for I L3 and IL5 (9,10). Association with beta c convert s GMCSF Ralpha from a low affinity to a high affinity receptor for GMCSF ( 9 11). The shared usage of beta c underlies the synergism between GMCSF, I L3, and I L5 in their effects on myeloid cell differentiation and activation (1, 2). Recombinant protein corresponding to human Leu20-Gly320, with a C-terminal 10-His tag expressed in NSO cells (P15509) Activity: Measured by its ability to inhibit GMCSF dependent proliferation of TF1 human erythroleukemic cells. The ED50 for this effect is typically 1.25ug/ml in the presence of 40pg/ml of rhGMCSF. Applications: Suitable for use in ELISA. Other applications not tested. Recommended Dilution: Optimal dilutions to be determined by the researcher. Storage and Stability: Lyophilized and reconstituted products are stable for 6 months after receipt at -20C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store at -20C. 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.
