M-Phase Phosphoprotein 10 (MPHOSPH10)

MPHOSPH10 encodes a protein that is phosphorylated during mitosis. The protein localizes to the nucleolus during interphase and to the chromosomes during M phase. The protein is thought to be part of the U3 small nucleolar ribonucleoprotein complex, which is involved in rRNA processing.Sequence analysis predicted that the 681-amino acid protein has a PEST sequence and 6 coiled-coil alpha helices containing acidic and basic stretches found in many nucleolar proteins. Cell fractionation and immunoblot analysis confirmed the nuclear and nucleolar localization of MPHOSPH10. Detailed examination of different phases of the cell cycle by immunofluorescence microscopy showed that MPHOSPH10 colocalizes with fibrillarin and is a component of U3 small nucleolar ribonucleoproteins (snoRNPs).