RNA and ssDNA-binding protein that may play specific roles during transcription initiation at distinct promoters. Binds to ssRNA containing the consensus sequence 5'-AGGUAA-3' (PubMed:21256132). Can enter the preinitiation complex together with the RNA polymerase II (Pol II). . This is the function of TAF15 (TATA-box binding protein associated factor 15, ENSG00000270647).