High affinity chimeric human granulocyte-macrophage colony-stimulating factor receptor carrying the cytoplasmic domain of the beta subunit but not the alpha subunit transduces growth promoting signals in Ba/F3 cells.

Granulocyte-macrophage colony-stimulating factor receptor (GMR) is composed of two distinct subunits alpha and beta, and the cytoplasmic domains of both subunits are essential to transduce signals. We further analyzed the role of the cytoplasmic domain of each subunit by constructing chimeric subunits, designated alpha/beta and beta/alpha, by exchanging cytoplasmic domains of the alpha and beta subunits of hGMR. Reconstituted high-affinity chimeric hGMRs, hGMR(alpha/beta,beta/alpha) and hGMR(alpha/beta,beta), as well as the wild type hGMR(alpha,beta), transduced signals in Ba/F3 cells. These observations indicate that the original configuration between the extracellular and the cytoplasmic domains of the hGMR(alpha,beta) subunits is not obligatory, and that hGMR(alpha/beta,beta) transduced signals through the cytoplasmic domain of the beta subunit in an oligomeric form, without involvement of the cytoplasmic domain of the alpha subunit.