Hetero-oligomeric complex between the G protein-coupled estrogen receptor 1 and the plasma membrane Ca2+-ATPase 4b [Cell Biology]

April 6th, 2015 by Tran, Q.-K., VerMeer, M., Burgard, M. A., Hassan, A. B., Giles, J.

The new G protein-coupled estrogen receptor 1 (GPER/GPR30) plays important roles in many organ systems. The plasma membrane Ca2+-ATPase (PMCA) is essential for removal of cytoplasmic Ca2+ and for shaping the time courses of Ca2+-dependent activities. Here we show that PMCA and GPER/GPR30 physically interact and functionally influence each other. In primary endothelial cells, GPER/GPR30 agonist G-1 decreases PMCA-mediated Ca2+ extrusion by promoting PMCA tyrosine phosphorylation. GPER/GPR30 overexpression decreases PMCA activity, and G-1 further potentiates this effect. GPER/GPR30 knockdown increases PMCA activity, while PMCA knockdown substantially reduces GPER/GPR30-mediated phosphorylation of the extracellular signal related kinase (ERK1/2). GPER/GPR30 coimmunoprecipitates with PMCA with or without treatment with 17beta-estradiol, thapsigargin or G-1. Heterologously expressed GPER/GPR30 in HEK 293 cells colocalizes with PMCA4b, the main endothelial PMCA isoform. Endothelial cells robustly express the PDZ post-synaptic density protein (PSD)-95, whose knockdown reduces the association between GPER/GPR30 and PMCA. Additionally, the association between PMCA4b and GPER/GPR30 is substantially reduced by truncation of either or both their C-terminal PDZ-binding motifs. Functionally, inhibition of PMCA activity is significantly reduced by truncation of the C-terminal PDZ-binding motif on GPER/GPR30. These data strongly indicate that GPER/GPR30 and PMCA4b form a hetero-oligomeric complex in part via the anchoring action of PSD-95, in which they constitutively affect each other functionally. Activation of GPER/GPR30 further inhibits PMCA activity through tyrosine phosphorylation of the pump. These interactions represent crosstalk between Ca2+ signaling and GPER/GPR30-mediated activities.