(b) Regulatory partner: interaction with regulatory proteins can control the activity of PRMTs

PRMTs	Regulatory partner	Biological role	Reference
PRMT5	MEP50	Required for PRMT5 activation	[29]
	SWI/SNF chromatin complex	Elevates the activity of MEP50-PRMT5 toward histone substrates	[30]
	Exon junction complex component and RNA-binding protein Y14	Enhances MEP50-PRMT5 activity toward Sm proteins	[31]
PRMT1	Orphan nuclear receptor TR3 (NR4A1)	Inhibits PRMT1 enzyme activity	[32]
	BTG1-binding chromatin assembly factor 1 (CAF1)	Negatively regulates PRMT1 activity	[33]
	BTG1	Increases PRMT1 activity	[34]
	PRMT2	Stimulates PRMT1 activation	[35]
PRMT3	Tumor suppressor DAL1	Blocks PRMT3 methyltransferase ability	[36]
PRMT7	CCCTC-binding factor like (CTCFL)	Increases PRMT7 activity	[37]