I think the premise is sort of an advanced idea, but I always, as nage, inhale to integrate uke's one point into myself and then exhale to complete the throw. Both pieces are important. I think that for uke it sort of depends on the attack. With a strike I inhale before execution of the attack and then exhale on impact. With a grab I think it varies depending on what you wish to accompish with the grab. If the intent is drive back then the same respiratory pattern is followed. If the intent is to draw in nage, then the reverse is done.
At least this is all the ideal. I occasionally find myself not following my own advice. And I firmly believe that this is not an introductory level idea. I don't tell this to new people anymore because it doesn't make sense to their bodies. I think technique must be integrated at least to the point where it's possible to carry out the movement without having to think about which foot goes where and which hand does what.
From the nage perspective I think this is all most illustratable in kokyudosa. After that the kokyunage's seem pretty good ways to catch the idea. After all, what does "kokyu" mean again?