Background: Many rapid nongenomic glucocorticoid actions are mediated by membrane-bound glucocorticoid receptors (GRs). S-palmitoylation is a lipid post-translational modification that mediates the membrane localization of some steroid receptors. A highly homologous amino acid sequence (663YLCM KTLLL671) is present in the ligand-binding domain of hGRα, suggesting that hGRα might also undergo S-palmitoylation.
Aim: To investigate the role of the motif 663YLCMKTLLL671 in membrane localization of the hGRα and in mediating rapid nongenomic glucocorticoid signaling.
Methods and results: We showed that the mutant receptors hGRαY663A, hGRαC665A and hGRαLL670/671AA, and the addition of the palmitoylation inhibitor 2-bromopalmitate did not prevent membrane localization of hGRα and co-localization with caveolin-1, and did not influence the biphasic activation of mitogen-activated protein kinase (MAPK) signaling pathway in the early time points. Finally, the hGRα was not shown to undergo S-palmitoylation.
Conclusions: The motif 663YLCMKTLLL671 does not play a role in membrane localization of hGRα and does not mediate the nongenomic glucocorticoid actions.