Table 1.

Subset of RGG-box proteins (see Table S1 in Supplementary Information for full list).

No. (#)a	Name (ID)	RGG domain (residue numbers)	Other RNA-binding motifsb	Functions/Comments Re/Pf (For details and references see Table S1)
1	Shadoo Q5BIV9	RGGARGSARGGVRGG (28–42)		PrP family member. Likely attached to cell membrane by GPI anchor.
12	hnRNP U Q00839	RGGGHRGRGGFNMRGGNFRGGAPGNRGG (701–728)		RGG box first identified when a 26-residue sequence (MRGGNFRGGAPGNRGGYNRRGN) found to be sufficient for RNA binding. Expected involvement in splicing, pre-mRNA processing and stabilizes specific mRNAs. R
21	HABP4 Hyaluronan binding protein 4 Q5JVS0	RGGPRGGMRGRGRGG (185–199)		Also constitutes a hyaluronan binding motif, (R/K–X(7)-R/K) where X is not acidic. Binds strongly and specifically to hyaluronan and weakly to RNA. Involved in mRNA transport, chromatin remodeling, regulation of transcription. R/P
26	EWS Ewing sarcoma Q01844	RGGFDRGGMSRGGRGGGRGGMGSAGERGG (304–332) and RGGPGGMRGGRGGLMDRGGPGGMFRGGRGGDRGGFRGGRGMDRGGFGGGRRGG (565–617)	1 RRMc	Found on cell surface, nucleus and cytoplasm. Is a transcriptional activator but this activity can be repressed by RGG box. May be involved in pre-mRNA splicing and transport. Suggested that EWS protein acts as a receptor or binding protein for ligands on cell surface, such as nucleic acids, and thus might mediate extracellular and nuclear events. R/P
32	FMRP Fragile X Mental Retardation Protein Q06787	RGGGGRGQGGRGRGG (534–548)	2 KHd	Binds many mRNA transcripts. Transports mRNA from nucleus to cytoplasm. Involved in neural plasticity through translational repression. R/P
33	Nucleolin P19338	RGGGRGGFGGRGGGRGGRGGFGGRGRGGFGGRGGFRGGRGG (656–696)	4 RRM	Found on cell surface, nucleus and cytoplasm. RGG box is necessary for efficient RNA binding but the RRMs are required for specific RNA recognition. Duplex DNA, ssDNA and RNA are all effective ligands. Acts as cell surface receptor—binds cytokine MK and HB-19 through its RGG box. R/P
34	G3BP1 Ras GTPase-activating protein-binding protein 1 Q13283	RGGLGGGMRGPPRGG (435–449)	1 RRM	Role in ras-signaling pathway affecting cell proliferation and survival as well as involved in RNA metabolism. Cleaves MYC mRNA and has helicase activity. Combining these functions, suggested to be member of novel sub-class of RBPs which act at level of RNA metabolism in response to cell signaling, thus allowing cell to rapidly control protein activity at a stage after transcription. R/P

^anumber of protein as appears in Table S1.

^bRNA-binding motifs in addition to the RGG box.

^cRRM = 80–90 amino acid sequence containing a RNP-1 (octapeptide) and RNP-2 (6 amino acid) consensus sequences.

^dK homology region as in hnRNP K.

^eRNA binding.

^fProtein binding.