Table 2.

IMAC-enriched specific granule-associated proteins identified by LC-MS/MS.

Protein Description	Peptide	Role in Neutrophil Function	Potential Kinase Motif^a
*Unstimulated*
Proline-rich synapse-associated protein 2(proSAP1)	GGS*LLSIGE^#GGF	Clusters vesicle membrane proteins to actin	Rho kinase (ROCK)
Gamma-aminobutyric acid (GABA) A receptor	GFSQMPTSSVKDETND^#NITIF	GPCR, PMN chemoattractant receptor	GPCR kinase, PAK/MLK
*Stimulated*
Complement component 1	VD^#VPCS*HFCNNF	Serine protease	TAK1
RAB3 interacting protein 3	RST*E^#QRPLLE^#RTTTRSRST	Rab-specific effector	Protein Kinase C
RAB3 interacting protein 3	KVVGGKMTES*GRLCAF	Rab-specific effector	Raf kinase
Paracingulin	VLE^#TE^#GS*QE^#STVIR	RhoGTPase regulator	Casein kinase 1
RAB21	DT*AGQE#RFHALGPIY	Vesicle targeting	Casein kinase 1a
Protein kinase C, alpha	TRPTICQY*	Kinase	Csk (Src)
G protein-coupled receptor 126	GS*NQNEIVSL	GPCR	Casein kinase 2b
G Protein receptor kinase 5	KVNSQFVVNLAY^AYETKD	Ser/Thr GPCR Kinase	Tec kinase, JAK2
Muted	GT*AGSAHLIIKD^#L	Biogenesis of granules	MAPK11
Dynein	AAHMADYS*VF	Vesicular motor protein	TAK1
RAN binding protein 3	KLNEVSSD^#AN RENAAAESGS E-SS*SQEATPE	Essential to nucleocytoplasmic transport	Casein kinases(for all S*)
Gamma-taxilin	RT*DPPD GQQDSECNRNKE^#KT	Syntaxin-binding protein, Ca²⁺-dependent exocytosis	MAPK9
PKC-delta-interacting protein kinase	VKE^#TAHD^#LDVKS*PPEPRS	Kinase, PKC inhibition blocks exocytosis of MMP-9	Multiple MAPKs
Slac2-b	H KTSCDSLD^#LSSAALPDSSPS K	Rab27-specific effector	Multiple MAPKs (for all S*)
Dedicator of cytokinesis 3(DOCK3)	KLDSMVSE^#GKGD^#E^#S*YRE	Regulates RhoGTPase activation	Casein kinase 2
Cdc42 effector protein 4	RDSSSLSSCTSGILE^#ERS	Control of actin polymerization	PKG2, Dyrk1

Peptide modification searches identified residues modified by methyl esterification of D and E (^#) and STY phosphorylation (*)

for each phosphorylated residue, as identified by Group Prediction System 2.1 (GPS) under high stringency [74]