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. Author manuscript; available in PMC: 2007 May 2.
Published in final edited form as: Mol Cell Proteomics. 2006 Dec 23;6(3):548–564. doi: 10.1074/mcp.D600007-MCP200

Table 1.

Transmembrane proteins localized to the plasma membrane identified by tandem mass spectrometry in human platelets and SAGE analysis in mouse megakaryocytes. Proteins are arranged according to families. Information is given on general function or specific function in platelets, where known. Several proteins are predominantly expressed on intracellular membranes and platelet α-granules and are translocated to the plasma membrane on activation. General information was obtained from NCBI, Swiss-Prot/TrEMBL and PubMed databases. The number of transmembrane domains (No. of predicted TMDs) in each protein was predicted with TMHMM v.2.0 (25). The highest number of unique peptides (No. of unique peptides) identified in a single mass spectrometry experiment are shown. The search algorithm (Mascot and/or Sequest) used to identify each protein is indicated, as is the method used to enrich transmembrane proteins (biotin/NA, biotinylation and NeutrAvidin affinity chromatography; FFE-IM, free flow electrophoresis-intracellular membrane fraction; FFE-PM, free flow electrophoresis-plasma membrane fraction; WGA, wheat germ agglutinin affinity chromatography). All proteins were identified by two or more peptide hits with at least one of the search algorithms. The number of SAGE tags (No. of SAGE tags) identified in mouse megakaryocytes is indicated in the final columns. Transcripts for 37 out of 44 proteins (84%) identified by MS/MS analysis of human platelets were identified in mouse megakaryocytes by SAGE. A question mark in the SAGE tag column indicates that the transcript could be present, but that there is currently not enough sequence information in the public databases for the identification of SAGE tags.

Family name (Protein name) Swiss-Prot/TrEMBL accession Function No. of predicted TMDs No. of unique peptides Search algorithm Enrichment No. of SAGE tags
Cadherin superfamily
protocadherin FAT 2 Q9NYQ8 Calcium-dependent cell-adhesion protein 1 2 Mascot WGA, FFE-PM ?
Ig superfamily and associated proteins
basigin P35613 Associates with carboxylate transporters; undergoes homophilic binding; function in platelets is not known 2 3 Sequest WGA 26
CD226 Q15762 Involved in intercellular adhesion and modulation of signaling; supports platelet adhesion to endothelial cells 1 5 Mascot, Sequest biotin/NA, WGA 3
CD84 O15430 Member of the SLAM family of homophilic adhesion receptors; stabilizes platelet-platelet interactions during thrombosis 1 4 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 3
endothelial cell-selective adhesion molecule Q96AP7 Found at tight junctions in endothelial cells; function in platelets is not known 1 3 Mascot, Sequest biotin/NA, FFE-PM 9
FcR γ-chain P30273 Present as a complex with the collagen receptor, GPVI; the ITAM in the FcR γ-chain is critical for GPVI signaling 1 2 Mascot, Sequest biotin/NA 23
G6f Q7Z5H2 G6f gene is found within the MHC class III; interacts with Grb2 when phosphorylated; function in platelets is not known 1 4 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM 7
GPVI Q9UIF2 Major signaling receptor for collagen; present as a complex with FcR γ-chain 1 3 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 6
MHC class I antigen (HLA-A) Q8MHP8 Presentation of antigens to the immune system 1 6 Mascot, Sequest biotin/NA 80 (total)
MHC class I antigen B-52 P30490 Presentation of antigens to the immune system 1 4 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM 80 (total)
MHC class I antigen Cw-15 Q07000 Presentation of antigens to the immune system 1 8 Mascot, Sequest biotin/NA, FFE-PM 80 (total)
ICAM 2 P13598 Ligand for β2-integrins; function in platelets is not known 1 3 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 2
JAM1 Q9Y624 Plays a role in tight junction formation and transmigration; function in platelets is not known 1 4 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM 5
JAM3 Q9BX67 May participate in cell-cell adhesion distinct from tight junctions; function in platelets is not known 1 3 Mascot, Sequest biotin/NA, FFE-PM 0
FcγRIIA P12318 Low affinity IgG receptor; mediates platelet activation by immune complexes via an ITAM regulated pathway 1 2 Mascot, Sequest biotin/NA Not in mouse
PECAM-1 P16284 Major platelet receptor; undergoes homotypic binding; inhibits platelet activation by collagen and VWF 1 12 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 7
TLT-1 Q8IWY2 Found on platelet α-granules and translocates on activation; contains an ITIM; supports late stage platelet activation 1 2 Mascot, Sequest biotin/NA, FFE-IM 13
Integrin family
α2 integrin subunit P17301 α2β1 mediates platelet adhesion to collagen 1 8 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 0
α6 integrin subunit P23229 α6β1 mediates platelet adhesion to laminin 1 12 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 47
αIIb integrin subunit P08514 αIIbβ3 is the major platelet adhesion and aggregation receptor 1 15 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 136
β1 integrin subunit P05556 associates with α2, α5 and α6 integrin subunits in platelets 1 8 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 14
β3 integrin subunit P05106 associates with αIIb and αv integrin subunits in platelets 1 17 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 41
Leucine-rich repeat family
GPIX P14770 Subunit of the GPIb-IX-V complex that binds VWF 1 5 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 11
GPV P40197 Subunit of the GPIb-IX-V complex that binds VWF 1 11 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 9
GPIbα P07359 Subunit of the GPIb-IX-V complex that binds VWF 1 5 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 21
GPIbβ P13224 Subunit of the GPIb-IX-V complex that binds VWF 1 4 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 31
LRRC32 protein Q14392 Not known 1 2 Mascot, Sequest biotin/NA 0
Peptidase family
ADAM 10 O14672 Proteolytic release of cell surface proteins, including TNFα and ephrin-A2; function in platelets is not known. 1 5 Mascot, Sequest biotin/NA, FFE-PM 11
ECE-1 P42892 Metabolism of big endothelin-1 to endothelin-1 1 2 Mascot, Sequest FFE-IM, WGA 0
Protein tyrosine phosphatase family
DEP-1 Q12913 Regulates contact inhibition of cell growth; function in platelets is not known 1 11 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 1
Selectin family
P-selectin P16109 Found on platelet α-granules and translocates on activation; mediates interaction with microparticles and leukocytes 1 11 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 13
Steroid receptor family
membrane associated progesterone receptor component 1 O00264 Receptor for progesterone; function in platelets is not known 1 2 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM 9
membrane associated progesterone receptor component 2 O15173 Receptor for progesterone; function in platelets is not known 1 4 Mascot, Sequest FFE-IM, FFE-PM 1
type I sigma receptor Q99720 Interacts with endogenous steroid hormones (progesterone and testosterone); function in platelets is not known 1 2 Mascot, Sequest FFE-IM 1
Tetraspanin family
CD9 P21926 Major platelet tetraspanin; associates with platelet glycoproteins 4 4 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM 34
Tspan-9 O75954 Function in platelets is not known 4 2 Mascot, Sequest biotin/NA, FFE-PM 5
Tspan-33 Q86UF1 Function in platelets is not known 4 3 Mascot, Sequest FFE-PM 3
Tyrosine protein kinase family
EphB1 P54762 Supports late stage aggregation via interaction with ephrin-B1 1 2 Mascot, Sequest biotin/NA 0
Miscellaneous
adipocyte plasma membrane-associated protein Q9HDC9 May play a role in adipocyte differentiation; function in platelets is not known 1 3 Mascot, Sequest FFE-IM, FFE-PM 2
BAT5 O95870 BAT5 gene is found within the MHC class III; function in platelets is not known 2 2 Mascot, Sequest FFE-IM 2
CD36 P16671 Putative receptor for collagen and thrombospondin in platelets 2 5 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 0
CD92 Q96KU3 Probable choline transporter; function in platelets is not known 9 2 Sequest FFE-PM 5
sodium/potassium transporting, β 3 polypeptide P54709 Non-catalytic component of a Na+/K+-ATPase; responsible for establishing and maintaining resting membrane potential 1 3 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM 3
solute carrier family 2, facilitated glucose transporter member 3 P11169 Facilitative glucose transporter; present in platelet PM and α-granules; required for glucose uptake by platelets 10 2 Mascot, Sequest FFE-IM, FFE-PM 11
STIM1 Q13586 A Ca2+ sensor that links Ca2+ store depletion from the ER with store-operation Ca2+ influx from the PM 1 5 Sequest FFE-IM, FFE-PM 2
stomatin, isoform a P27105 Act as a cytoskeletal anchor in erythrocytes; present in platelet α-granules 1 5 Mascot, Sequest biotin/NA, FFE-IM, FFE-PM, WGA 12
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