Related Experiment Video
Updated: Jun 7, 2026

Mutagenesis and Analysis of Genetic Mutations in the GC-rich KISS1 Receptor Sequence Identified in Humans with Reproductive Disorders
Published on: September 4, 2011
Assessment of constitutive activity and internalization of GPR54 (KISS1-R)
Macarena Pampillo1, Andy V Babwah
1The Children's Health Research Institute, London, Ontario, Canada.
Abstract:
The kisspeptin/GPR54 signaling system positively regulates GnRH secretion, thereby acting as an important regulator of the hypothalamic-pituitary-gonadal axis. It also negatively regulates tumor metastases and placental trophoblast invasion. GPR54 is a G(q/11)-coupled GPCR and activation by kisspeptin stimulates PIP(2) hydrolysis and inositol phosphate (IP) formation, Ca(2+) mobilization, arachidonic acid release, and ERK1/2 and p38 MAP kinase phosphorylation. Recently, we reported that GPR54 displays constitutive activity and internalization in the heterologous human embryonic kidney 293 cell system. Given the physiological and clinical importance of GPR54 as well as other GPCRs, we present assays for measuring constitutive receptor internalization and activity. Specifically, we describe the use of immunofluorescence coupled to confocal imaging, flow cytometry and indirect receptor radiolabeling to measure constitutive receptor internalization, and IP turnover in intact cells to measure constitutive activity. While we use the FLAG-tagged GPR54 molecule as an example to describe these assays, the assays can be applied to a wide range of GPCRs.
Related Concept Videos
G-protein Coupled Receptors
G-protein Coupled Receptors
G Protein-coupled Receptors
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
G Protein-coupled Receptors
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
The Two-State Receptor Model
The binding affinity of a drug determines its interaction with one...
Transducer Mechanism: G Protein–Coupled Receptors
GPCRs are also called heptahelical, 7TM, or...

