The most straightforward resource is the String database:

1. Go to http://string-db.org

2. Select the “multiple sequences” tab

3. Paste a ‘FASTA’ file containing the identifiers and sequences of interest (see examples if not acquainted with FASTA)

4. Verify the protein sequences found by String

5. Analyze the PPI network.

Thank you Eyal Akiva :)

I also created a program to do this kind of research. I will compare the results.