UHMK1 is a novel splicing regulatory kinase

The U2AF Homology Motif Kinase 1 (UHMK1) is the only kinase that contains the U2AF homology motif (UHM), a common protein interaction domain among splicing factors. Through this motif, UHMK1 interacts with the splicing factors SF1 and SF3B1, known to participate in the 3’ splice site recognition and early steps of spliceosome assembly. Also, UHMK1 phosphorylates these splicing factors in vitro. However, the involvement of UHMK1 in RNA processing has not previously been demonstrated. Here, we used global phosphoproteomics to identify novel putative substrates in UHMK1-overexpressing or -depleted (knockdown) NIH3T3 cells and better characterize the function of this kinase in splicing and other biological processes.