Title : N-glycosylation and expression in human tissues of the orphan
GPR61 receptor
Abstract :
- A number of members of the G protein-coupled receptor class of cell surface receptors are 'orphans' with no known endogenous ligand
- One of these orphan receptors is GPR61 ; there are little data about its expression in human cells and tissues
- In this study, we investigated the post-translational modification of GPR61 by N-glycosylation at an identified consensus N-glycosylation site ( N12 ) and the impact of this modification upon the subcellular expression of the protein
- The N-glycosylation inhibitor tunicamycin reduced the apparent molecular weight of immunoreactivity associated with myc-tagged GPR61 by 1-2 kDa, which was comparable to the evident molecular weight of the myc-tagged N12S GPR61 mutant with disrupted consensus N-glycosylation site
- Analysis of GPR61 expression demonstrated that tunicamycin treatment reduced considerably heterologous expression of GPR61 in the cell membrane despite the N12S GPR61 mutant being readily expressed at the cell surface
- These results demonstrate that GPR61 is subject to N-glycosylation but suggest this is not a prerequisite for cell surface expression, although N-glycosylation of other proteins may be important for cell membrane expression of GPR61
- Expression of GPR61 protein was demonstrated at the cellular level in human hippocampus and human peripheral blood mononuclear cells
- In the latter, there was a significantly higher expression of GPR61 in the Th17 cell subset in comparison with resting CD4 + cells, which may point toward a potential role for the GPR61 receptor in autoimmune diseases
- This is the first report that GPR61 protein is subject to post-translational modification and is expressed in immune cell subsets and the hippocampus
- These findings will help guide studies to investigate the function of GPR61