Thus, a tribute to his mother has led to the discovery of the gene Listerin, Ltn1, E3 ubiquitin ligase and its effect on motor and sensory neuron degeneration.
Following Griffiths' advice, Kay moved to the United States and worked as a postdoc in the Nam-Hai Chua lab at Rockefeller University.
It was at the Nam-Hai Chua lab working with another postdoc named Ferenc Nagy that Kay stumbled upon the discovery that the chlorophyll binding gene CAB was regulated by a circadian clock.
There, Kay collaborated with Jeffrey C. Hall and discovered a cryptochrome mutant in fruit flies, also demonstrating that clock genes were distributed all over the body, which was named one of Science's top 10 breakthroughs in 1997.
He and his postdoctoral fellow John B. Hogenesch, realized that in order to discover novel mammalian clock genes one would have to leverage high throughput genomics techniques that were being developed at the time.
From 2012 to 2015, he served as a professor and the Dean of Dornsife College of Letters, Arts and Sciences at the University of Southern California (USC).
[6] In 1985, Kay and his colleagues found that the Cab gene was under circadian control in wheat and transgenic tobacco plants during his postdoctoral research.
[8] Based on this Cab:luc fusion technology, Kay set up luciferase imaging assays for large scale forward genetics screening and identified the first short period mutant of TOC1 gene.
[10] Kay identified ELF3, GI, Lux, CHE and PRRs as core clock genes and studied their role in the circadian regulation loop.
His work on functional analyses of core clock genes, as well as ccg, successfully connected circadian rhythm with the control of development, like seedling, growth and flowering.
[13] Kay found evidence that there are multiple phototransduction pathways, and contributed to the discovery and functional analysis of many photoreceptors, including phytochrome, cryptochrome, ZTL and LKP2 and their roles in circadian rhythms.
[14] Kay applied the first clock gene fusion, Per:luc, in Drosophila melanogaster which allows monitoring of its rhythm at the single animal level.
It was here, with the use of automation and large-scale genomics technology, that Kay and collaborating colleagues found that the mammalian clock consisted of more than just one feedback loop.
In 2002, Kay and his team were able to show the role of melanopsin, a photosensitive photopigment in retinal ganglion cells, in detecting light for the master circadian oscillator located in the suprachiasmatic nucleus (SCN) in the hypothalamus of the brain.
[21] Kay's research on intercellular networks has the potential to contribute to drug therapies by identifying compounds that affect the circadian pathways.