Plays an important role in the elongation step of protein synthesis. P1 and P2 exist as dimers at the large ribosomal subunit. Yeasts contain 4 individual small ribosomal A proteins (RPA) which can be classified into two couples of similar but not identical sequences. Each couple is distinctly related to one of the two A proteins present in multicellular organisms. Rpa3 and rpa4 are essential for cell survival, whereas rpa1 and rpa2 are not. Belongs to the eukaryotic ribosomal protein P1/P2 family.