Cytoplasmic and nuclear fractionation from HEK293T cells

The poly(A) tail appended to the 3' end of many eukaryotic transcripts plays a key role in the stability, nuclear transport, and translation of the RNA. These roles are largely mediated by the Poly(A) Binding Proteins (PABPs) that coat the poly(A) tails and interact with various proteins involved in the biogenesis and function of the RNA. While it is well established that the nuclear PABP (PABPN) binds newly synthesized poly(A) tails and is apparently replaced by the cytoplasmic PABP (PABPC) on transcripts exported to the cytoplasm, the distribution of transcripts for different genes or isoforms of the same gene on these distinct PABPs has not been investigated on a genome-wide scale. Here, we analyzed the identity, splicing status, poly(A) tail size, and translation status of RNAs co-immunoprecipitated with endogenous PABPN or PABPC in human cells. At steady state, many protein coding and non-coding RNAs exhibit strong bias for association with PABPN or PABPC. While PABPN-enriched transcripts more often were incompletely spliced and harbored longer poly(A) tails and PABPC-enriched RNAs tended to have longer half-lives and higher translation efficiency, there are curious outliers. Overall, our study reveals the landscape of RNAs bound by PABPN and PABPC, providing new details that support and advance the current understanding of the roles these proteins play in poly(A) tail synthesis, maintenance and function. Overall design: 2 biological replicates were crosslinked and collected; subcellular fractionation was performed to separate the cytoplasm from the nuclear fraction