Post-transcriptional regulatory strategies and extraribosomal functions of human rpL3

rpL3 gene produces in addition to canonical mRNA isoform normally translated in protein, an alternative isoform, containing a PTC (premature termination codon) degraded by NMD (Nonsense mediated mRNA decay). Moreover, overexpression of rpL3 causes an increase of alternative isoform level, unproductive, which results in rpL3 decrease. This negative feedback loop triggered by the accumulation of ribosomal protein, is a strategy that finely regulates the amount of ribosomal protein to an appropriate level, especially relevant to any extra-ribosomal functions of rpL3. hnRNP H1, NPM and KHSRP are involved with different roles in the post-transcriptional regulation of rpL3 gene and we hypothesize a model of regulation that provides a sequence of interactions between these proteins and rpL3 transcript. This post-transcriptional regulation, that provides the association of alternative splicing and NMD, can be very important to finely modulate the rpL3 amount available to extra-ribosomal functions.