tailieunhanh - Báo cáo khóa học: Human PABP binds AU-rich RNA via RNA-binding domains 3 and 4

Poly(A) binding protein (PABP) binds mRNApoly(A) tails and affects mRNA stability and translation. We show here that there is little free PABP in NIH3T3 cells, with the vast majority complexed with RNA. We found that PABP in NIH3T3 cytoplasmic lysates and recombinant human PABP can bind toAU-richRNA with high affinity. Human PABP bound an AU-rich RNA withKdin the nMrange, which was only sixfold weaker than the affinity for oligo(A) RNA. | Eur. J. Biochem. 271 450-457 2004 FEBS 2003 doi Human PABP binds AU-rich RNA via RNA-binding domains 3 and 4 Rosemary T. Sladic1 Cathy A. Lagnado1 Christopher J. Bagley1 2 and Gregory J. Goodall1 2 1 Division of Human Immunology and Hanson Institute Institute of Medical and Veterinary Science Adelaide Australia Department of Medicine The University of Adelaide Australia Poly A binding protein PABP binds mRNA poly A tails and affects mRNA stability and translation. We show here that there is little free PABP in NIH3T3 cells with the vast majority complexed with RNA. We found that PABP in NIH3T3 cytoplasmic lysates and recombinant human PABP can bind to AU-rich RNA with high affinity. Human PABP bound an AU-rich RNA with Kd in the nM range which was only sixfold weaker than the affinity for oligo A RNA. Truncated PABP containing RNA recognition motif domains 3 and 4 retained binding to both AU-rich and oligo A RNA whereas a truncated PABP containing RNA recognition motif domains 1 and 2 was highly selective for oligo A RNA. The inducible PABP iPABP was found to be even less discriminating than PABP in RNA binding with affinities for AU-rich and oligo A RNAs differing by only twofold. These data suggest that iPABP and PABP may in some situations interact with other RNA regions in addition to the poly A tail. Keywords PABP iPABP poly A binding protein RNA-binding protein AU-rich element. Poly A binding protein PABP occupies the poly A tails of mRNA transcripts in eukaryotic cells and has important influences on both the stability and the translation of mRNA 1 . Studies with in vitro systems are consistent with PABP acting as a physical impediment to limit the access of exoribonuclease to the 3 -end of polyadenylated RNA 2-4 while more complex interactions also impact on mRNA stability. Through interactions with proteins that assemble on the 5 -cap structure of mRNA PABP participates in the effective circularization of mRNA. One .