Figure The coupling of Stachel-activated GPR56 and disease associated
mutations of the receptor with Gα13.
The effect of BFPP mutations on
Gα11coupling
GPR56 was previously shown to couple with Gαq/11 as a
GPR56-CD81-Gαq/11 complex [34]. In human glioma
cells, stimulation of GPR56 with its agonistic monoclonal antibodies
resulted in signaling through Gαq dependent Rho pathway
[35]. GPR56 or BFPP mutants of the receptor were co-expressed
with Gα11 and GRK-based Gβδ biosensors to assess the
effect of each mutation on the G protein coupling when the receptor is
stimulated with its Stachel peptide. For this, HEK293 cells were
treated with the 1mM P7 Stachel peptide and Gα11coupling and heterotrimeric G protein activation was measured as
nanoBRET signal. GPR56C91S gave statistically indistinguishable nanoBRET
compared with wild-type receptor. A decrease in nanoBRET
indicative of G protein coupling defect was measured in all otherBFPP mutants, however GPR56R565W did not show any
Gα11 coupling.