REGULATION OF THE RIBOSOME BIOGENESIS FACTOR HYVH1 BY SRC-MEDIATED PHOSPHORYLATION

In this study, we investigate cellular effects of a novel Src-mediated phosphorylation site at Tyr179 on hYVH1. We observed that this phosphorylation event attenuates hYVH1's stress granule disassembly function, enhances shuttling of hYVH1 to the nucleus, and promotes hYVH1 partitioning to the 60S ribosomal subunit. Quantitative proteomics reveal that Src co-expression with hYVH1 reduces formation of ribosomal species that represent stalled intermediates through the alteration of associating factors that promote translational repression. Collectively, these results implicate hYVH1 as a novel Src substrate and is the first demonstrated role of tyrosine phosphorylation regulating the activity of a YVH1 ortholog. Moreover, the ribosome proteome alterations point to a collaborative function of hYVH1 and Src in maintaining translational fitness.