Association of newly synthesized poly(A) polymerase with four distinct polypeptides.
Nuclear poly(A) polymerase was isolated from [35S]methionine-labeled hepatoma McA-RH 7777 cells and subjected to DEAE-Sephadex chromatography. Flow-through and low salt wash fractions containing poly(A) polymerase activity were pooled and subjected to immunoblot analysis using anti-tumor type poly(A) polymerase antibodies and a biotinylated second antibody. The immune complex contained a single 48-kDa polypeptide band corresponding to the tumor-type enzyme. When immunoprecipitations were carried out using the same fraction and antibodies, at least five 35S-methionine-labeled proteins with approximate molecular masses of 74, 48, 35, 30, and 22 kDa were observed. Pulse-chase studies did not indicate a precursor-product relationship between the immunoprecipitated proteins. Preimmune sera did not react with poly(A) polymerase or other components in the protein complex. These data show that poly(A) polymerase exists as part of a complex with at least four other polypeptides and suggest that these polypeptides may be involved in the cleavage and/or polyadenylation reactions.
Hengst
J A
JA
Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey 17033.
Georgoff
I
I
Isom
H C
HC
Jacob
S T
ST
D000818:Animals; D002460:Cell Line; D015151:Immunoblotting; D008114:Liver Neoplasms, Experimental / Q000201:enzymology; D046911:Macromolecular Substances; D008715:Methionine / Q000378:metabolism; D009713:Nucleotidyltransferases / Q000096:biosynthesis*; D011062:Polynucleotide Adenylyltransferase / Q000096:biosynthesis* / Q000302:isolation & purification
D046911:Macromolecular Substances; D008715:Methionine; D009713:Nucleotidyltransferases; D011062:Polynucleotide Adenylyltransferase