Is there a way to obtain taxonomy IDs of organisms with associated protein sequences?

Question

[lorenz]

I want to get a list of taxonomy IDs from a taxonomic group. If I enter the taxon ID (ex. txid4751[Organism]) in taxonomy database in NCBI, there are a lot of entries, some of them don't have associated protein sequences. I would only need the IDs of those organisms with protein sequences. A much as possible, searching for that taxon in the protein database, and downloading the data, then extracting the taxon IDs, is not an option. Is there an easier way to do this? Any help would be greatly appreciated.