title: Three distinct forms of nuclear poly(A) polymerase.
abstract: Poly(A) polymerase activities have been solubilized from rat liver nuclei and purified by chromatography on Bio-Gel A-1.5M, DEAE-Sephadex and CM-cellulose. Three distinct forms of nuclear poly(A) polymerase have been resolved by chromatography on CM-cellulose. According to their sequence of elution from CM-cellulose these enzyme activities have been termed A, B and C. Enzymes A and B are Mn2+ -dependent, enzyme C requires Mg2+. With the same chromatographic step on CM-cellulose the Mn+ -dependent poly(A) polymerase activities were separated from a Mn2+ -dependent enzyme system capable of synthesizing RNA-primed poly(U), poly(G) and poly(C). The effect of different nuclear and cytoplasmic RNA primers on the rate of poly(A) formation suggests enzyme A to be responsible for the elongation of preexisting poly (A) chains.  The phosphorylated derivated derivative of cordycepin, 3'-deoxyadenosine 5'-triphosphosphate (3'-dATP), which is known to inhibit nuclear poly(A) synthesis in vivo, also impairs poly(A) formation in vitro. It is shown that 3'-dATP very probably is not incorporated into poly(A)invitro, suggesting that 3'-dATP primarily affects the catalytic activities of the poly(A) polymerase species rather than directly blocking chain elongation.
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D003839:Deoxyadenosines / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008345:Manganese / Q000494:pharmacology; D009713:Nucleotidyltransferases / Q000378:metabolism*; D011062:Polynucleotide Adenylyltransferase / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats
chemical_list: D003839:Deoxyadenosines; D007527:Isoenzymes; D008345:Manganese; D000255:Adenosine Triphosphate; D009713:Nucleotidyltransferases; D011062:Polynucleotide Adenylyltransferase; D008274:Magnesium