Rate My Professor Ajith Karunarathne

Ajith Karunarathne, Ph.D., is an Associate Professor of Chemistry and Chemical Biology in the Department of Chemistry at Saint Louis University. He earned a B.S. from the University of Sri Jayewardenepura, Sri Lanka, a Ph.D. in Biological Chemistry from Michigan State University, and completed postdoctoral training in signal transduction and optogenetics at Washington University School of Medicine under Professor N. Gautam. As Principal Investigator of the Molecular Cell Lab, Karunarathne leads research at the intersection of biological chemistry, chemical biology, and molecular pharmacology. His group adopts a reductionist approach to dissect biological processes at the subcellular level, multiplexing properties of signaling molecules to engineer tools and pathways that reveal disease chemistry. They combine cellular signaling with single-cell and subcellular optogenetics to probe how cells communicate and behave, developing opsin-based optogenetic tools optimized for spectral, signaling, and chemical properties suitable for in vivo use. Additional innovations include phototropin- and cryptochrome-based tools that regulate G protein signaling independent of GPCRs, providing dynamic insights into pathways orchestrating migration, invasion, proliferation, and insulin receptor-mediated glucose uptake.

Karunarathne's laboratory further employs computational and hybrid chemical-cellular methods to examine how the photoreceptor chromophore retinal elicits cytotoxic reactions upon blue light exposure, linking these processes to vision and skin damage. They also pioneer photopharmacology, administering photoactivatable molecules followed by targeted light irradiation to activate, inhibit, or modulate cellular functions precisely at subcellular, cellular, tissue, or organ levels. His scholarly output includes numerous peer-reviewed articles in prestigious journals such as Scientific Reports, Cell Signal, Journal of Biological Chemistry, and Proceedings of the National Academy of Sciences. Notable publications encompass "Blue light excited retinal intercepts cellular signaling" (Scientific Reports, 2018), recognized as a top 100 attention-grabbing publication; "Subtype-dependent regulation of Gβγ signaling" (Cell Signal, 2021); "Dissociation of the G protein βγ from the Gq-PLCβ complex partially attenuates PIP2 hydrolysis" (J Biol Chem, 2021); "Microcystins: Biogenesis, Toxicity, Analysis, and Control" (Chem Res Toxicol, 2020); and "A short C-terminal peptide in Gγ regulates Gβγ signaling efficacy" (Mol Biol Cell, 2021). These contributions enhance molecular tools for signaling interrogation and photochemical disease interventions.