Binds to the 3' poly(U) terminus of nascent RNA polymerase III transcripts, protecting them from exonuclease digestion and facilitating their folding and maturation (PubMed:3192525, PubMed:2470590). In case of Coxsackievirus B3 infection, binds to the viral internal ribosome entry site (IRES) and stimulates the IRES-mediated translation (PubMed:12384597). Interacts with DDX15. May interact with RUFY1. Phosphorylated. The phosphorylation sites are at the C-terminal part of the protein. The N-terminus is blocked. Sera from patients with systemic lupus erythematosus (SLE) often contain antibodies that react with the normal cellular La protein as if this antigen was foreign.