Plays an essential role in transcription initiation and cap-stealing mechanism, in which cellular capped pre-mRNAs are used to generate primers for viral transcription. Recognizes and binds a wide range of cap structures of target pre-RNAs which are subsequently cleaved after 10-13 nucleotides by the viral protein PA. Plays a role in the initiation of the viral genome replication and modulates the activity of the ribonucleoprotein (RNP) complex. Influenza RNA polymerase is composed of three subunits: PB1, PB2 and PA. Interacts (via N-terminus) with PB1 (via C-terminus). Interacts with nucleoprotein NP (via N-terminus). Belongs to the influenza viruses PB2 family.