Table 2.

Stress Granules and related foci induced upon stress. The stress-induced formation of granules containing polyadenylated RNAs is conserved through evolution, and may depend or not on the inactivation of eIF2alpha. The resulting foci may have distinct composition in different organisms. SGs induced in Drosophila by heat shock or arsenite contain classical mammalian SG components. Stress Granules from C. elegans, yeast and trypanosomes are markedly different. Bonafide Stress Granules are apparently induced in budding yeast exposed to glucose starvation or arsenite, or in fission yeast upon osmotic stress or heat shock. T. brucei respond to heat shock forming cytoplasmic SGs that contain PABP, eIF4E, eIF3 and exclude PB components, thus resembling mammalian SGs. In contrast, T. cruzi cells assemble visible granules containing polyadenylated RNA and the PB components DHH1 and XRNA when exposed to nutritional starvation (see also Fig. 1D).

Organism	Stressor	RNA granulea	eIF2α phosphorylation	Kinase	Components included	Components excluded	References
Mammals	Arsenite or ER-stress	SG	YES	HRI or PERK respectively	PolyA(+) RNA, PABP, TIA-1/R, eIF3, G3BP, eIF4G, 40S, others.	60S, HSP27, TTP, Dcp-1, Dcp-2, Hedls, GW182, Lsm1-7, others.	[10]
	Heat shock	SG	YES		HSP27, polyA(+) RNA, PABP, TIA-1/R		[23]
	Pateamine, hippuristanol, tiRNA, energy deprivation	SG	NO		PolyA(+) RNA, PABP, TIA-1/R, eIF3, G3BP, 40S, eIF4E, TTP (for energy deprivation), others	Hedls, 60S, Dcp1, Rck/p54	[24], [25], [26], [27]
	UV	SG	YES		PolyA(+) RNA, PABP, TIA-1/R	HSP27	[23]
D. melanogaster	Heat shock	SG	NO		PolyA(+) RNA, FMR1, eIF4E, eIF3, PABP, Rox8 (TIA1), 18S rRNA	DCP1, RPL P0	[28]
	Arsenite	SG	YES	PEK and GCN2b	PolyA(+) RNA, FMR1, eIF4E, eIF3, PABP, Rox8 (TIA1), 18S rRNA	DCP1, RPL P0	[17], [28]
T. brucei	Heat shock	SG	NO		eIF4E1 to 4, eIF2A, eIF3B, ABP1/2	DHH1/Rck/, XRNA/XRN1	[29]
	Carbon-source starvation	mRNA granules			PABP1, UBP1, polyA(+) RNA		[30]
T. cruzi	Carbon-source starvation	mRNA granules			PABP1/2, eIF4E, TcDhh1/Rck, XRNA/XRN1, TcUBP1 to 4, 5a and 6b, polyA(+) RNA	eIF3D, TcS15(40S), TCL3 (60S)	[30]
	Nutritional stress	Cytoplasmic foci			5′ tRNA halves, 3′ tRNA halves		[31]
S. pombe	Osmotic or heat shock	Stress-dependent foci			rRNA, eIF4E, Sum1/eIF3i, p116/eIF3b, Int6/eIF3e		[32]
S. cerevisiae	Heat shock	SG	NO		eIF3, Pab1p/PABP, eIF4G2, Rps30A (40S), Ngr1/TIAR, Pub1/TIA1, Dcp2p Dhh1/Rck	Rp125 (60S), eIF2α	[33]
	Glucose starvation	Pab1-containing PBs			PolyA(+) RNA, Pab1p/PABP, eIF4E, eIF4G. Partially Dcp2p	eIF3	[37]
	Glucose starvation	EGP bodies			eIF4E, eIF4G, Pab1p/PABP	eIF3b, eIF4AI, eIF2α, eIF2Bγ,	[38]
	Glucose starvation	SG	YES	Gcn2	Pub1/TIA-1, Ngr1/TIAR, Pbp1/Ataxin-2, Pab1p/PABP, eIF4GI, eIF4GII, eIF4E, Eap1/4EBP, Hrp1, Ygr250c, Gbp2	eIF3, PeIF2α	[18]
	Glucose starvation or arsenite	SG			Pbp1(Ataxin-2), Pub1(TIA1), Pbp4p, Lsm12, Dhh1(Rck/p54)		[34]
C. elegans	Heat shock/sperm depletion in female worms	RNP foci (oocytes)			RNA, MEX-3, DCP-2, CAR-1/Rap55, CGH-1/Rck, PABP, TIA1		[35]
C. reinhardtii (chloroplast)	Oxidative stress/high light/FCCP/UV/phosphate deprivation	cpSG			cPABP, S21 (40S), mRNA	L12 (60S), L2 (60S)	[36]

^aNames given by the authors. PBs are not included.

^bPEK main kinase, GCN2 secondary role.