The human Pat1b protein: a novel mRNA deadenylation factor identified by a new immunoprecipitation technique.
The complex of the yeast Lsm1p-7p proteins with Pat1p is an important mRNA decay factor that is involved in translational shutdown of deadenylated mRNAs and thus prepares these mRNAs for degradation. While the Lsm proteins are highly conserved, there is no unique mammalian homolog of Pat1p. To identify proteins that interact with human LSm1, we developed a novel immunoprecipitation technique that yields virtually pure immunocomplexes. Mass-spec analysis therefore identifies mostly true positives, avoiding tedious functional screening. The method unambiguously identified the Pat1p homolog in HeLa cells, Pat1b. When targeted to a reporter mRNA, Pat1b represses gene expression by inducing deadenylation of the mRNAs. This demonstrates that Pat1b, unlike yPat1p, acts as an mRNA-specific deadenylation factor, highlighting the emerging importance of deadenylation in the mRNA regulation of higher eukaryotes.
Totaro
Antonio
A
Department of Experimental Neurosciences, Fondazione Santa Lucia, Rome, Italy.
Renzi
Fabrizio
F
La Fata
Giorgio
G
Mattioli
Claudia
C
Raabe
Monika
M
Urlaub
Henning
H
Achsel
Tilmann
T
D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods*; D011061:Poly A / Q000032:analysis; D014176:Protein Biosynthesis; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D020871:RNA Stability; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism
D004268:DNA-Binding Proteins; C464824:LSM1 protein, human; C526510:PATL1 protein, human; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011061:Poly A