- The methylosome, a 20S complex containing JBP1 and pICln, produces dimethylarginine-modified Sm proteins. Friesen, W.J., Paushkin, S., Wyce, A., Massenet, S., Pesiridis, G.S., Van Duyne, G., Rappsilber, J., Mann, M., Dreyfuss, G. Mol. Cell. Biol. (2001)