Non-catalytic component of the methylosome complex, composed of PRMT5, WDR77 and CLNS1A, which modifies specific arginines to dimethylarginines in several spliceosomal Sm proteins and histones . This modification targets Sm proteins to the survival of motor neurons (SMN) complex for assembly into small nuclear ribonucleoprotein core particles. Might play a role in transcription regulation. The methylosome complex also methylates the Piwi proteins (PIWIL1, PIWIL2 and PIWIL4), methylation of Piwi proteins being required for the interaction with Tudor domain-containing proteins and subsequent localization to the meiotic nuage .
Subcellular locations: Nucleus, Cytoplasm
Nuclear in Leydig cells and cytoplasmic in germ cells during fetal testicular development. In adult testis, predominantly nuclear. Subcellular location varies from nuclear to cytoplasmic in various tumors .
Highly expressed in heart, skeletal muscle, spleen, testis, uterus, prostate and thymus. In testis, expressed in germ cells and Leydig cells, but not in peritubular myocytes, nor in Sertoli cells. Expressed in prostate cancers, in seminomas and in Leydig cell tumors.