title: Molecular cloning and characterization of a novel isoform of the non-canonical poly(A) polymerase PAPD7.
abstract: Non-canonical poly(A) polymerases (ncPAPs) catalyze the addition of poly(A) tail to the 3' end of RNA to play pivotal roles in the regulation of gene expression and also in quality control. Here we identified a novel isoform of the 7th member of ncPAPs: PAPD7 (PAPD7 l), which contains 230 extra amino acids at the amino terminus of the previously identified PAPD7 (PAPD7 s). In sharp contrast to the inactive PAPD7 s, PAPD7 l showed robust nucleotidyl transferase activity when tethered to an RNA. A region required for the activity was localized to 187-219 aa, and this region was also required for the nuclear retention of PAPD7 l. Western blot analysis revealed that 94 kDa band (corresponding to PAPD7 l) but not 62 kDa band (corresponding to PAPD7 s) detected by PAPD7 antibody was specifically depleted by treatment with PAPD7 siRNA in both HeLa and U2OS cells. These results suggest that PAPD7 l is the major and active isoform of PAPD7 expressed in cells.
authors: Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan.
authors: Koichi
authors: K
authors: Ogami
authors: Rihe
authors: R
authors: Cho
authors: Shin-ichi
authors: S
authors: Hoshino
mesh_terms: D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000201:enzymology; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D019913:Nuclear Localization Signals / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012316:RNA Nucleotidyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D007527:Isoenzymes; D024101:Mitochondrial Proteins; D019913:Nuclear Localization Signals; D012316:RNA Nucleotidyltransferases; C567954:TENT4B protein, human; D012321:DNA-Directed RNA Polymerases; C555258:MTPAP protein, human; D004259:DNA-Directed DNA Polymerase; C118146:TENT4A protein, human