My research is focused on the role that a family of enzymes called ADP-ribosyltransferases (ARTDs) plays in brain function, such as learning and memory. Mammals, including humans, produce 17 ARTD family members, each of which performs the same chemical reaction, called ADP-ribosylation, which involves the transfer of ADP-ribose to protein targets. ADP-ribosylation is essential for learning: mice trained to recognize new objects show increased levels of ADP-ribosylation in brain regions involved in recollection, while inhibition of ARTD function blocks learning and memory. But little is known about which members of the enzyme family, the majority of which are expressed in the brain, are responsible for this essential brain function due to the difficulty identifying the direct protein targets of the individual ARTD family members. To address this challenge, I will engineer ARTDs so that I can identify their direct protein targets, an essential first step toward understanding how ARTDs function in neurons to promote learning in the brain. This work will shed new light on the molecular mechanisms that drive the still-mysterious process of learning and neuronal function.