He currently serves as the Ricardo Miledi Professor of Neuroscience at the University of Wisconsin–Madison, where he is also an investigator of the Howard Hughes Medical Institute (HHMI).
Chapman has made important contributions in three related areas: the molecular mechanisms by which Ca2+ triggers exocytosis in neurons and neuroendocrine cells, the structure and dynamics of exocytotic fusion pores, and the mechanisms by which botulinum and tetanus neurotoxins act on neurons to block exocytosis.
His laboratory was the first to reconstitute Ca2+-triggered membrane fusion in vitro using purified components,[2] and he has used this approach to make numerous crucial contributions concerning the mechanism by which proteins catalyze the merger of lipid bilayers.
He is also a leader concerning our understanding of exocytotic fusion pores, using both cell- and nanodisc-based approaches to reveal their dynamics, composition, and structure.
[2] Other major contributions include on going studies to assign functions to orphaned synaptic vesicle proteins and to understand the function of all members of the synaptotagmin family of membrane trafficking proteins; this latter work has revealed a number of novel insights into synaptic plasticity.