Table I. Phosphorylation changes in response to 5 min of osmotic stress.

Phosphopeptides showing 2-fold or greater change in phosphorylation in response to 5 min of 0.3 m mannitol treatment and additional phosphopeptides selected for targeted proteomic analysis are shown. Phosphorylation sites that could not be localized to one residue are indicated by multiple residues inside brackets. MS/MS spectra for the listed phosphopeptides are documented in Supplemental Figure S1. n/a, Not applicable.

ATG Accession No.	Protein	Phosphopeptide	Fold Change	se	Targeted MS Validation
Kinases/signaling related
AT2G01690	Vac14	AT[pS]GVPFSQYK	12.55	1.01	Yes
AT1G10940a	SnRK2.1/4/5/10	S[pT]VGTPAYIAPEVLSR	6.18	2.06	Yes
AT1G53165	MAP4Kα1	SS[pS]ASEDSISNLAEAK	4.87	0.72	Yes
AT1G16270	MAP3K Raf18	TV[pS]GGGIETEAR	2.50	1.24	Yes
Proteasome/ubiquitin related
AT2G26590	RPN13	AGNLVVPNLSSEV[pS]DVTSSSGPVK	3.84	0.23	n/a
AT2G47970	NPL4 family protein	SIPGAPPVTPAG[pS]FGR	2.29	0.18	n/a
AT3G63000	NPL41 (NPL4-LIKE)	GGPAVTPAG[pS]FGR	2.06	0.09	n/a
5′ mRNA decapping
AT5G13570	DCP2	[pTS]VGGNGTATVESQNR	4.48	0.04	n/a
AT3G13300	VCS (varicose)	TP[pS]ADYSVDR	5.69	0.95	Yes
		ESITSAS[pS]VAQALSR	5.50	2.01	n/a
		NLDVS[pS]VEEISR	2.18	0.002	n/a
		TSGLPSQTSGAGSAYATLPQLPL[pS]PR	0.49	0.06	n/a
AT3G13290	VCR (varicose related)	TS[pS]ADYFYVR	3.98	0.53	n/a
Cytoskeleton
AT1G04820a	TUA2/4/6	TIQFVDWCP[pT]GFK	2.80	0.30	Yes
AT5G19770a	TUA1/3/5	TVQFVDWCP[pT]GFK	1.98	0.06	Yes
AT2G21380	Kinase motor related	[pSSS]TPTSTVYNSGGVTGSR	2.53	0.93	n/a
Channels/pumps
AT3G58730	Vacuolar ATPase D subunit	GI[pS]INAAR	2.91	0.66	Yes
AT5G60660	Aquaporin PIP2F	ALGSFGSFG[pS]FR	2.48	0.11	Yes
		ALGSFG[pS]FGSFR	2.09	0.13	No
AT2G36380	ATP-binding cassette transporter PDR6	LP[pT]YDRLR	2.49	0.78	n/a
Vesicle trafficking related
AT1G08800	MyoB1	ALLTQI[pS]ASR	5.65	0.07	Yes
AT4G19490	VPS54	SI[pS]DASSQSLSSILNNPHGGK	2.68	0.14	n/a
AT4G11740	SAY1	AASG[pS]LAPPNADR	1.92	0.09	Yes
AT1G79830	GC5	QN[pS]AFENGSLPR	2.78	0.004	Yes
Metabolism related
AT1G77120	ADH1	IIGVDFN[pS]K	0.22	0.10	No
AT5G05600	Oxidoreductase	VQ[pS]LAESNLSSLPDR	3.20	0.49	No
AT5G40390	SIP1	SD[pS]GINGVDFTEK	1.51	0.06	Yes
AT3G58460	RBL15	[pTLS]TARDPTAPAGETDPNLHAR	2.04	0.13	n/a
Other/unknown
AT2G21230	bZIP30	SI[pS]GEDTSDWSNLVK	2.70	0.19	Yes
AT1G72410	COP1-interacting related	LSLGGG[pS]ADFSK	4.73	0.26	Yes
AT3G03050	Cellulose synthase-like CSLD3	[pS]NLSTNSDAAEAER	2.10	0.01	n/a
AT2G01190	PB1 domain containing	GF[pS]DSDTNVNR	2.29	0.25	Yes
AT5G64430	PB1 domain containing	LFLFPASSGFG[pS]QSSTQSDRDR	2.00	0.42	n/a
AT2G32240	PICC defense responsive	DIDLSFS[pS]PTK	1.49	0.001	Yes
AT5G56980	A70 defense responsive	AP[pS]IIDR	1.55	0.02	Yes
AT5G35430	TPR domain containing	[pTSS]LLSSSVASDTLR	2.61	0.12	n/a
AT1G22060	Unknown	SVV[pS]GDLSGLAQSPQK	2.37	0.54	n/a
AT5G58510	Unknown	TN[pS]VNQSPTDAIR	2.10	0.01	n/a
AT5G42950	GFY domain containing	[pSPSS]DLLSILQGVTDR	2.00	0.23	n/a

^aPeptide matches multiple family members.