I am trying to create lower thirds for a project. The graphic involves solid text with a black, 90% opacity, banner behind it. I exported the graphic using PR4444 with alpha channel. When I placed the alpha channel video into premiere, the banners opacity seems to have dropped significantly as shown in the pictures below (I used a gray background in both applications to point out the difference).
Ae defaults to blending in a gamma-encoded space, but Pr defaults to blending in a linear space (when GPU acceleration is on). This probably accounts for the difference in compositing that you're seeing. To fix this, you can either change Ae to match Premiere, or change Premiere to match Ae.
To change Ae, open your project preferences and either set the working space to a linear space, or check the "Blend colors using 1.0 gamma" box.
To change Pr, open your sequence settings and uncheck "Composite in linear color (requires GPU acceleration or max render quality)".