I have a refseq ID of a protein from E.coli and I want to find homologs of this protein. I ran Blast against refseq database but I got a lot of sequences most of which were from Ecoli again. I decided to run PSI-Blast to get more divergent species, but I do not exactly know if my result are real homologs or false positives. what is your idea for finding homologous protein sequences from more divergent species? And what can I do for selecting the real (but not false positive) hits?