Table 2.

Effects of two major functional classes of Rab proteins on Golgi ribbon organization

Class	Rab	Isoform	Golgi ribbon phenotype produced by Rab inactivation or activation					References
			Inactivation			Activation
			Depletion by RNAi	GDP-locked Rab overexpression	Rab GAP overexpression	Wild-type Rab overexpression	GTP-locked Rab overexpression
1A	Rab1	Rab1a	Redistribution to the ER	Fragmented (1.5-h expression)	Lost of Golgi apparatus to the ER with punctate structures remaining	Normal	Unknown	(Bard et al., 2006; Haas et al., 2007; Monetta et al., 2007; Nuoffer et al., 1994; Romero et al., 2013; Wilson et al., 1994)
		Rab1b	Redistribution to the ER with punctate GM130	Redistribution to the ER with punctate GM130		Elongation of Golgi cisternae (EM1)
1B	Rab18	Rab18	Normal/fragmented2	Normal	Unknown	Normal/fragmented2	Fragmented	(Dejgaard et al., 2008)
	Rab30	Rab30	Fragmented	Fragmented	Unknown	Normal	Normal	(Dejgaard et al., 2008; Kelly et al., 2012)
	Rab41	Rab41	Fragmented	Fragmented	Unknown	Normal	Normal	(Liu et al., 2013)
	Rab43	Rab43	Unknown	Fragmented	Fragmented	Normal	Unknown	(Dejgaard et al., 2008; Haas et al., 2007)
2	Rab63	Rab6a	Little effect on the Golgi ribbon and by EM1, Golgi cisternae number increases, Golgi ribbon is longer and continuous	Slightly more compact ribbon	Unknown	Redistribution to the ER	Redistribution to the ER	(Ferraro et al., 2014; Jiang and Storrie, 2005; Martinez et al., 1997; Micaroni et al., 2013; Storrie et al., 2012; Sun et al., 2007; Young et al., 2005)
		Rab6a′
	Rab33	Rab33a	Unknown	Unknown	Unknown	Unknown	Unknown
		Rab33b	More continuous Golgi ribbon	Normal	Unknown	Redistribution to the ER	Redistribution to the ER	(Jiang and Storrie, 2005; Starr et al., 2010; Valsdottir et al., 2001)

¹Golgi ribbon phenotype is obtained by electron microscopy

²Results showed by Dejgaard et al (2008) might well be expected to show differences with Rab mutant or careful consideration of expression time. Further studies are needed

³The other two isoforms of Rab6, Rab6b and Rab6c, are not shown here. Rab6b is predominantly expressed in neuronal cells and Golgi-associated (Opdam et al., 2000). Rab6c is involved in cell cycle progression (Young et al., 2010)