Table 2.

SR proteins in humans and rice (47)

	Rice	Humans
Number of SR proteins	22	12
RS domains	＞50 aas long; ＞20% RS content or RS dipeptide	＞50 aas long; ＞40% RS content of RS or SR repeat
RRM domains	1-2 Conserved	1-2 Conserved
Additional domains	1-2 zinc knuckle; acidic –terminal extension rich in Ser and Pro	1 zinc knuckle
Not rice specific sub-groups
SR subfamily	2 RRMs with SWQDLKD motif	SF2/ASF: 2 RRMs with SWQDLKD motif
RSZ subfamily	1 RRM, 1 zinc knuckle	SF7/9G8: 1 RRM, 1 zin knuckle
SC subfamily	1 RRM+SR domain	SF2/SC35: 1 RRM+SR domain
Rice specific sub-groups
SCL subfamily	1 RRM+ 1 N-terminal charged extension	N/A
SC2Z subfamily	1 RRM+ 2 zinc Knuckles + 1 acidic–terminal extension rich in Ser and Pro
RS subfamily	2 RRMs but without SWQDLKD motif