Putative nucleotidyltransferase required for several aspects of embryonic development including normal development of the eye (PubMed:27103078, PubMed:30487245). It is unclear whether it displays nucleotidyltransferase activity in vivo (PubMed:27271801). Binds single-stranded RNA (ssRNA) (PubMed:27271801). {ECO:0000269|PubMed:27103078, ECO:0000269|PubMed:27271801, ECO:0000269|PubMed:30487245}. This is the function of MAB21L1 (mab-21 like 1, ENSG00000180660).