Pen Tool - isolating value or position when moving keyframes

Hi Premiere Users,

I'm using the pen tool to adjust audio keyframes in the timeline and am looking for a feature that I can't find.  In at least one other editing platform I've used, one could hold down a modifier button (like alt/option, for example) while moving a keyframe, and it would allow you to change ONLY its value or ONLY its position.  This was incredibly useful, as I almost never want to do both at once.  Yet, in Premiere, whenever I try to adjust one, despite my best efforts to hold the pen inhumanly steady in one direction, the keyframe ends up going somewhere I don't want it to. 

Does there exist a feature in Premiere to do this with more control, and specify for which variable you want to adjust a keyframe?

Thanks!