Myosin phosphatase (MP) holoenzyme is a protein phosphatase-1 (PP1) type Ser/Thr
specific enzyme that consists of a PP1 catalytic (PP1c) and a myosin phosphatase target
subunit-1 (MYPT1). MYPT1 is an ubiquitously expressed isoform and it targets PP1c to its
substrates. We identified the protein arginine methyltransferase 5 (PRMT5) enzyme of the
methylosome complex as a MYPT1-binding protein uncovering the nuclear MYPT1-
interactome of hepatocellular carcinoma cells. It is shown that PRMT5 is regulated by …

Results MYPT1 nuclear interactome: interaction with PRMT5 of the methylosome complex.
Initial reports have already described the presence of MYPT1 in the nucleus but its exact
subnuclear localization and function remained unknown13. MYPT1, PP1cα/γ 1 and PP1cδ
were distributed in the cytoplasmic and nuclear subcellular fractions (Fig. S1A). Specific
activity measured in the presence of 2 µ M inhibitor-2 (I2) which is a highly selective inhibitor
of PP1, but does not influence PP2A activity27 suggested that~ 60% of total phosphatase …