Using X ray crystallographic techniques and electron microscopy, Kobilka (Nobel Prize 2012) and colleagues described the very complex nucleotide exchange and interactions at the molecular level of the alpha subunit of a Gs at the moment of its activation by an adrenergic receptor. 
The authors showed that the structural links between the receptor binding surface and the nucleotide binding pocket of the Gs undergo higher levels of hydrogen deuterium exchange than would have been predicted from the crystal structure of the beta 2 adrenergic receptor-Gs complex. Then the team, using advanced computer techology, explained the complex molecular interactions between these two molecules, revealing many details that were neither expected nor predicted before this achievement.

Order of authorship in the original publication: Chung, Rasmussen, ...Kobilka....

(Thanks to Juan Weiss for this reference and its interpretation.)