Table 1.

Summary of the targeting requirements of the core TOC components.

TOC component	Targeting and integration signals		Outer envelope receptor/Protein components	Cytosolic factors	Energy requirements	References
Toc75	Cleavable, N-terminal, bipartite signala,b,c	Targeting		Unknown	ATPa	aTranel et al., 1995
		Transit peptidea,b	TOC translocona,b,c			bTranel and Keegstra, 1996
		Membrane Integration				cInoue and Keegstra, 2003
		Poly-glycine regionc	β-barrel translocase (?) (OEP80d?)			dSchleiff and Soll, 2005
Toc34	GTPase domain e,f		Proteinaceous componentse,h	AKR2k	ATPh	eChen and Schnell, 1997
	Transmembrane domain and C-terminal tail e,g			Hsp17.8l	GTP/GDPe,f	fQbadou et al., 2003
			Toc34g			gDhanoa et al., 2010
			Toc75i			hTsai et al., 1999
						iKim and Hwang, 2013
						kBae et al., 2008
						lKim et al., 2011
Toc159	M-domain m,n,p		Toc34, Toc75t	Unknown	GTP/GDPq,r	mMuckel and Soll, 1996
	GTPase domain q,r,s					nLee et al., 2003
						pLung and Chuong, 2012
						qHiltbrunner et al., 2001
						rBauer et al., 2002
						sSmith et al., 2002
						tWallas et al., 2003