National Institute of Health
Connecting Peptides and Antibodies to Probe Cell Surface Receptors
SESSION 1: PEPTIDE TOOLS & PROBES
Sunday, June 25, 2023, at 09:00 am - 09:25 am
Peptides and antibodies represent two leading modalities for targeting protein receptors expressed on the surface of mammalian cells. Endogenous peptides often serve as leads for developing tools and therapeutic candidates for probing receptor function, but they often suffer from insufficient selectivity, especially when targeting members of large receptor families such as G protein-coupled receptors, GPCRs. Alternatively, antibodies are prized in biomedical research for their high specificity but typically lack any biological effect, inhibition or activation, when targeting receptors with orthosteric sites embedded within transmembrane domains.
To leverage and expand the favorable properties of peptides and antibodies we have developed methods to create conjugates comprised of peptidic GPCR ligands and antibody fragments, nanobodies. Synthesis is performed through a combination of solid-phase peptide synthesis, site-specific labeling of recombinantly expressed nanobodies, and click chemistry. These conjugates show properties superior to those of antibodies or peptides alone, including receptor specificity and in vivo biological activity.
We have further elaborated on this approach by developing chemistry that facilitates the covalent linkage between a nanobody and its binding partner through templated amide bond formation. This approach showed that covalent linkage of an agonist to its receptor resulted in enduring signaling. These tools should prove useful for mechanistic investigations of peptide-binding receptors and provide a new class of molecules with useful properties for biomedical investigation.
Dr. Ross Cheloha is a Stadtman Tenure Track Investigator at the National Institutes of Health in the National Institute of Diabetes, Digestive, and Kidney Diseases. He works on the development of new tools to study G protein-coupled receptors, with a focus on peptide chemistry, antibody engineering, and bioconjugation. He leads a group of postbaccalaureate and postdoctoral scientists focused on the development of antibody-ligand conjugates to uncover new biological mechanisms and outline novel paths towards therapeutic development.
Ross conducted his Ph.D. in the Department of Chemistry at the University of Wisconsin in the lab of Prof. Sam Gellman, where he developed α/β-peptide analogues of parathyroid hormone that possessed specialized properties. He did his postdoctoral work at MIT and Harvard Medical School in the lab of Prof. Hidde Ploegh, where he applied single domain antibody conjugates to interrogate cell biology and immunology. He is passionate leveraging approaches from disparate fields to provide tools to address vexing scientific questions.