Previous studies in this laboratory have identified two distinct nuclear poly(A) polymerases, a 48 kDA tumor type enzyme and a 36-38 kDA liver type enzyme. To investigate the tissue and species specificity of these enzymes, nuclear extracts were prepared from various rat tissues, pig brain and two human cell lines. These as well as whole cell extract from yeast were probed for the two enzymes by immunoblot analysis using polyclonal anti-tumor poly(A) polymerase antibodies or autoimmune sera which contain antibodies specific for the liver type enzyme. Results indicate that both tumor and liver type enzymes are conserved across species ranging from rat to human. The yeast enzyme does not appear to be immunologically related to the liver or the tumor type poly(A) polymerase. The liver type enzyme appears to be specific for normal tissues whereas the tumor type enzyme is detected only in tissues in a "tumorigenic" state or cell lines originating from tumor tissues.