Table 1. Peptide substrates displaying statistically significant altered phosphorylation when peptide arrays are incubated with lysates of sucrose-treated plants as compared to lysates from sorbitol-treated plants. Peptides were selected for their importance in human signal transduction and represent human sequences. The results show the results of A. thaliana treated for 1 hour with either sucrose or the inactive osmotic control, both at a concentration of 100 mM. Subsequently, cells were lysed and analysed for their capacity to in vitro phosphorylate peptide arrays (for details, see main text).

PEPTIDE ON CHIP	tTEST	P UP/DOWN	KINASE	PROTEIN	REMARK
RERLKSTNDKG	0,004	UP	AKT, S6K, CK2	Estrogen receptor, alpha	PKB
RKRSTSLNERP	0,030	DOWN	AKT1	Tuberin	PKB
RKRRWSKPESR	0,046	DOWN	ATK1	Ataxin 1	PKB
TVKENTKDELK	0,042	UP	BCR	AF6
QLGPPSPVKMP	0,015	UP	cdc2	Pituitary tumor-transforming protein 1
LRQLRSPRRKQ	0,001	DOWN	cdc2	Ras-like protein Rab4
GDKKETPPRPR	0,011	UP	cdk5	MEK1
MSTESMIRD	0,039	UP	CK1	TNF alpha
TTTKPSLSGKG	0,002	UP	CK1, GSK3beta	Beta-catenin	2 phosphorylation sites in peptide
TTGGESKDELE	0,009	UP	CK2	Occludin
IRYIESLQELL	0,023	UP	CK2	Myogenic factor 5
NRSFLSLKHTP	0,004	UP	GSK3beta	Notch2
PVKRTSPLQTP	0,039	DOWN	MAPK (JNK), PKC	Bcl 2	PKC during G2/M for anti-apoptosis
TIDPKSPQSPE	0,035	DOWN	MAPK (p38)	Solute carrier family 9, isoform A1	Na/H-antiporter
IGEGTYGVVYK	0,039	DOWN	Myt, WEE	CDC2	completely conserved in arabidopsis
VPKRKSLVGTP	0,044	UP	PAK6	p21 activated protein kinase 6 (PAK6)	auto-P
GDRTSTFKGTP	0,047	UP	PDK1	PKN	PKC-like kinase
KERRFSRSDQL	0,012	UP	PKA	WT1	Zinc-finger
FTRRKSVKKEK	0,021	UP	PKA	PKA	auto-P
EKRKNSILNPI	0,028	DOWN	PKA, PKC	CFTR	ABC transporter, multi-drug resistance protein, pS700 by PKA
LTRIPSKKKYK	0,025	UP	PKC	PEA15	death effector domain (DED)-containing protein
LSPSPSSRVTV	0,039	DOWN	PKC	Lamin B1
KRQYGTISHGI	0,023	DOWN	PKC	Amyloid precursor like protein 2
KFRTPSFLKKN	0,043	DOWN	PKC	Adducin 3	cytoskeleton
ESLESTRRILG	0,007	UP	PKC	SNAP23	vesicle transport, 2 residues phosphorylated by PKC
ESRSGSNRRER	0,028	UP	PKC	WIP	Wiskott-Aldrich syndrome protein (WASP) interacting protein
RKRHNSISEKK	0,023	DOWN	PKG	Phospholipase C, beta 3	produces DAG and IP3
SSYRRTFGGKP	0,023	UP	ROCK	Desmin	Rho-associated kinase ROCK
EPKRRSKRLSK	0,043	DOWN	S6K, PKA, PKC	HMG14
KDEGSYTLEEP	0,024	UP	Tyr-K	Syndecan 3	possibly sugar-dependent (lectin domain)
TDEDIYLLGKK	0,022	UP	Tyr-K	Sialyltransferase 1
SKEPQYQPGDQ	0,030	UP	Tyr-K Csk	Fgr	Src2
GGDDIYEDIIK	0,020	UP	Tyr-K EGFR	VAV2	GEF of Rho-family GTPase
KENPEYLGLDV	0,031	DOWN	Tyr-K EGFR	ErbB2	Tyr-K receptor, auto-P
DGKEIYNTIRR	0,005	UP	Tyr-K EGFR, Tyr-K Lck	RasGAP	GAP1 (GTPase-activating proteins)
IPSVPYKPFKK	0,035	UP	Tyr-K Hck (Src-subfamily)	Guanine nucleotide releasing factor 2	GEF of Ras-like GTPases
EQRNVYKDYRQ	0,013	UP	Tyr-K Src	Dynamin 1	vesicular trafficking
FTNPVYKTLYM	0,044	UP	Tyr-K Src	Low density lipoprotein receptor-related protein 1	endocytosis
KDENYYKKQTH	0,011	UP	Tyr-K SYK	SYK	auto-P, SYK activates VAV
RQGKDYVGKIP	0,042	UP	Tyr-K VEGFR2	VEGF receptor 2	auto-P
KKYMETVKLLD	0,015	UP	VRK	Vaccinia related kinase 1	auto-P
MHRRHTDPVQL	0,046	UP		GRID	GRB2, Tyr-K signaling, Ras protein signal transduction
SLFDRTPTGEM	0,012	UP		Myosin light chain 1