Defense Date


Document Type


Degree Name

Master of Science


Anatomy & Neurobiology

First Advisor

Javier González-Maeso, PhD

Second Advisor

Melissa McGinn Greer, PhD

Third Advisor

Audrey Lafrenaye, PhD


G protein-coupled receptors (GPCRs) constitute the most numerous and diverse superfamily of cell membrane receptors. While GPCRs can perform signal transduction as monomers, evidence suggests they also function as homo- and hetero- dimers and oligomers. These diverse quaternary structures can affect GPCRs’ downstream cellular signaling, pharmacological properties, and regulation of internalization.

The single-molecule pulldown (SiMPull) assay combines a co-immunoprecipitation assay with single-molecule total internal reflection fluorescence (TIRF) microscopy and can be used to probe the stoichiometry of GPCR oligomers in mammalian cells.

This project replicates the SiMPull assay by confirming the quaternary structure of mGluR2 homodimers. Plasmid constructs SNAP-mGluR2-HA and SNAP-mGluR2 were expressed in Human Embryonic Kidney (HEK) 293 cells. Anti-HA antibodies selectively captured the SNAP-mGluR2-HA, which then pulled down SNAP-mGluR2 in complex.

Analysis on the proportion of photobleaching steps through binomial distribution confirmed that the vast majority of imaged mGluR2 complexes were homodimers. Successful replication of the SiMPull assay and confirmation of its efficacy has been important for establishing a base for future studies determining unknown stoichiometries of oligomeric GPCR assemblies.


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Available for download on Saturday, May 10, 2025