This is a probable transcription activator that specifically binds the purine-rich single strand of the PUR element located upstream of the c-Myc gene. May play a role in the initiation of DNA replication and in recombination. Homodimer, heterodimer with PURB and heterotrimer with PURB and YBX1/Y-box protein 1 (PubMed:10318844). Interacts with FMR1; this interaction occurs in association with polyribosome (PubMed:12147688). Belongs to the PUR DNA-binding protein family.