Two populations of Chinese hamster ovary (CHO) cells expressing similar numbers of recombinant human alpha2A-adrenergic receptors (α2A- AR) showed different capacity to inhibit adenylyl cyclase (AC) activity. Cells transfected with an integrating vector exhibited agonist-dependent inhibition of forskolin-stimulated AC, whereas cells transfected with a non-integrating episomal vector showed no inhibition. Fluorescent microscopy and flow cytometry revealed a very uneven receptor distribution in the episomally transfected cell population. Monoclonal cell populations were expanded from this parent population. Most clones lacked significant amounts of receptors, while a few expressed receptors at high density; these exhibited efficient agonist-dependent inhibition of forskolin-stimulated AC activity. Thus, dense receptor expression in only a few cells is not sufficient to evoke a significant inhibitory response in a functional assay where AC is stimulated in all cells. Consequently, a false negative result was produced. Furthermore, the cell population transfected with an integrating vector showed loss of homogeneity with increasing passage number. © 2004 Elsevier B.V. All rights reserved.
Björk, S., Vainio, M., & Scheinin, M. (2005). Uneven cellular expression of recombinant α2A- adrenoceptors in transfected CHO cells results in loss of response in adenylyl cyclase inhibition. Biochimica et Biophysica Acta - Molecular Cell Research, 1744(1), 38–46. https://doi.org/10.1016/j.bbamcr.2004.11.006