Masking RGB/Gloss texture with RGBA texture

I’m trying to setup an Earth with a RGB and Gloss channel. This works fine so far. But now im trying to display a Heatmap over this Earth. The RGBA Channel of the heatmap works fine, but the glossiness of the earth is making the heatmap hard to see where it reflects light. What would be a convenient way to mask the glossmap with the alpha of the RGBA heatmap? In a way that the glossiness stays everywhere except where the alpha of the heatmap kicks in.