Table 3. β-arrestin 1-interacting proteins under nonstimulated (-) condition

IPI accession Swiss-Prot Number of accession Gene symbol Protein name experiments number number detected Signal transduction Adaptor proteins IPI00293857 P49407 ARRB1 β-arrestin 1 8 IPI00027355 P32121 ARRB2 β-arrestin 2 7 IPI00021353 P10523 SAG S-arrestin (Retinal S-antigen) (48 kDa protein) (S-AG) (Rod photoreceptor arrestin) 4 IPI00003917 P36575 ARR3 X-arrestin (Arrestin-C) (Cone arrestin) (cArr) (Retinal cone arrestin-3) (C-arrestin) 4 IPI00216318 P31946 YWHAB 14-3-3 β/α (14-3-3 protein beta/alpha) (Protein kinase C inhibitor protein 1) (KCIP-1) (Protein 1054) 2 IPI00220642 P61981 YWHAG 14-3-3 γ (14-3-3 protein gamma) (Protein kinase C inhibitor protein 1) (KCIP-1) 2 IPI00018146 P27348 YWHAQ 14-3-3 θ (14-3-3 protein tau) (14-3-3 protein theta) (14-3-3 protein T-cell) (HS1 protein) 2 IPI00216319 Q04917 YWHAH 14-3-3 η (14-3-3 protein eta) (Protein AS1) 2 IPI00000816 P62258 YWHAE 14-3-3 ε (14-3-3 protein epsilon) (14-3-3E) 2 IPI00021263 P63104 YWHAZ 14-3-3 ζ/δ (14-3-3 protein zeta/delta) (Protein kinase C inhibitor protein 1) (KCIP-1) 2 IPI00465275 Q96S59 RANBP9 RanBPM (Ran-binding protein 9) (RanBP9) (RanBP7) (Ran-binding protein M) (BPM90) (BPM-L) 2

Protein kinases IPI00027251 Q15208 STK38 STK38 (Serine/threonine-protein kinase 38) (NDR1 protein kinase) (Nuclear Dbf2-related kinase 1) 2 SCY1-like 2 (SCY1-like 2 protein) (coated vesicle-associated kinase of 104 kDa) (Eukaryotic protein IPI00396218 Q6P3W7 SCYL2 2 kinase family protein) (CDNA FLJ10074 fis, clone HEMBA1001744, weakly similar to SCY1 IPI00013835 Q13574 DGKZ DGK ζ (Diacylglycerol kinase zeta) (Diglyceride kinase zeta) (DGK-zeta) (DAG kinase zeta) 2 DGK ε (Diacylglycerol kinase epsilon) (Diglyceride kinase epsilon) (DGK-epsilon) (DAG kinase IPI00003293 P52429 DGKE 2 epsilon) IPI00027658 P49619 DGKG DGK γ (Diacylglycerol kinase gamma) (Diglyceride kinase gamma) (DGK-gamma) (DAG kinase gamma) 2 p160ROCK ( Rho-associated protein kinase 1) (Rho-associated, coiled- coil-containing protein kinase 1) IPI00022542 Q13464 ROCK1 2 (p160 ROCK-1) (NY-REN-35 antigen) IPI00013981 P07947 YES c-Yes (Proto-oncogene tyrosine-protein kinase Yes)(p61-Yes) 2 IPI00412298 Q13535 ATR Serine/threonine-protein kinase ATR (Ataxia telangiectasia and Rad3-related protein) (FRAP-related 2

Phosphatases IPI00020950 P35813 PPM1A PP2Cα (Protein phosphatase 2C isoform alpha) (PP2C-alpha) (IA) (Protein phosphatase 1A) 2 IPI00026612 O75688 PPM1B PP2Cβ (Protein phosphatase 2C isoform beta) (PP2C-beta) 4

Trafficking IPI00216393 P09496 CLTA Clathrin light chain A 2 IPI00024067 Q00610 CLTC Clathrin heavy chain 2 AP-3 δ1 (Delta-adaptin) (AP-3 complex subunit delta-1) (Adapter-related protein complex 3 subunit IPI00411453 O14617 AP3D1 2 delta-1) (Delta-adaptin 3) (AP-3 complex subunit delta) Gaf-1 (Rab11 family-interacting protein 5) (Rab11-FIP5) (Rab11-interacting protein Rip11) (Gamma- IPI00022033 Q9BXF6 RAB11FIP5 2 SNAP-associated factor 1) (Phosphoprotein pp75) LRP4 (Low-density lipoprotein receptor-related protein 4 precursor) (Multiple epidermal growth factor-like IPI00306851 O75096 LRP4 2 domains 7) LRP-DIT (Low-density lipoprotein receptor-related protein 1B precursor) (Low- density lipoprotein receptor- IPI00032063 Q9NZR2 LRP1B 2 related protein-deleted in tumor) IPI00413140 Q05193 DNM1 dynamin-1 2

G protein- and small GTPase-related IPI00168858 Q5VZ06 RGS3 RGS3S (Regulator of G-protein signaling 3 isoform RGS3S) 2 IPI00005719 P62820 RAB1A Rab-1A (Ras-related protein Rab-1A, member Ras oncogene family) (YPT1-related protein) 2

Other signaling proteins IPI00075248 P62158 CALM1 Calmodulin (CaM) 3 Annexin II (Annexin A2) (Lipocortin II) (Calpactin I heavy chain) (Chromobindin-8) (p36) (Protein I) IPI00455315 P07355 ANXA2 2 (Placental anticoagulant protein IV) (PAP-IV) IPI00419647 Q9Y6C5 PTCH2 Patched 2 (Protein patched homolog 2) (PTC2) 2 IPI00414286 O75056 SDC3 Syndecan-3 (SYND3) 2

Nucleic acid binding DNA binding, chromatin structure and cell cycle regualtion IPI00217465 P16403 HIST1H1C Histone H1.2 (Histone H1d) 4 IPI00152785 P23527 HIST1H2BO Histone H2B (Histone H2B type 1-O) (H2B.n) (H2B/n) (H2B.2) 2 IPI00453473 P62805 HIST1H4A Histone H4 2 IPI00216730 Q8IUE6 HIST2H2AB Histone H2A (Histone H2A type 2-B) 2 IPI00219038 P84243 H3F3A Histone H3.3 (H3 histone, family 3A) 2 Transcription factor and transcription regulatory protein Nopp 140 (Nucleolar phosphoprotein p130) (Nucleolar 130 kDa protein) (140 kDa nucleolar IPI00292387 Q14978 NOLC1 8 phosphoprotein) (Nucleolar and coiled-body phosphoprotein 1) IPI00298696 Q13428 TCOF1 Treacle (Treacher collins franceschetti syndrome 1) 8 JBP1 (Protein arginine N-methyltransferase 5) (Shk1 kinase-binding protein 1 homolog) (SKB1Hs) IPI00441473 O14744 PRMT5 5 (Jak-binding protein 1) (72 kDa ICln-binding protein) IPI00549248 P06748 NPM1 Nucleophosmin (NPM) (Nucleolar phosphoprotein B23) (Numatrin) (Nucleolar protein NO38) 2 IPI00031960 O95602 POLR1A RPA194 (DNA-directed RNA polymerase I largest subunit) (RNA polymerase I 194 kDa subunit) 3 IPI00005179 O15160 POLR1C RPA40 (DNA-directed RNA polymerase I 40 kDa polypeptide) 2 PAF53 (DNA-directed RNA polymerase I-associated factor 53 kDa subunit) (RNA polymerase I IPI00478729 Q9GZS1 POLR1E 2 polypeptide E) (RNA polymerase I- associated factor 1) PAF49 (RNA polymerase I-associated factor PAF49) (Antisense ERCC1) (Anti-sense to ERCC-1 protein) IPI00012788 O15446 CD3EAP 3 (ASE-1) (CD3-epsilon-associated protein) (CD3E-associated protein) (CAST) ZNF265 (Zinc finger protein 265) (Zinc finger Ran-binding domain-containing protein 2) (Zinc IPI00029400 O95218 ZNF265 8 finger, splicing) Trap150 (Thyroid hormone receptor-associated protein 3) (Thyroid hormone receptor-associated IPI00104050 Q9Y2W1 THRAP3 3 protein complex 150 kDa component) Thymopoietin (Thymopoietin α) (Lamina-associated polypeptide 2 isoform alpha) (Thymopoietin isoform IPI00216230 P42166 TMPO 2 alpha) (TP alpha) (Thymopoietin-related peptide isoform alpha) (TPRP isoform alpha) YB-1 (Y-box transcription factor) (Nuclease sensitive element-binding protein 1) (Y-box-binding IPI00031812 P67809 YBX1 protein 1) (Y-box transcription factor) (CCAAT-binding transcription factor I subunit A) (CBF-A) 2 (Enhancer factor I subunit A) (EFI-A) (DNA-binding protein B) (DBPB) Tho4 (THO complex subunit 4) (Ally of AML-1 and LEF-1) (Transcriptional coactivator Aly/REF) IPI00328840 Q86V81 THOC4 2 (bZIP-enhancing factor BEF)

RNA processing and ribonucleoprotein Nop10 (H/ACA ribonucleoprotein complex subunit 3) (Nucleolar protein family A member 3) IPI00032853 Q9NPE3 NOLA3 2 (snoRNP protein NOP10) IPI00549342 Q5JRR2 RBM10 RNA binding motif protein 10 4 SAP 145 (Splicing factor 3B subunit 2) (Spliceosome-associated protein 145) (SF3b150) (Pre- IPI00221106 Q13435 SF3B2 2 mRNA-splicing factor SF3b 145 kDa subunit) IPI00604620 P19338 NCL Nucleolin (Protein C23) 3 SMD1 (Sm-D1) (Small nuclear ribonucleoprotein Sm D1) (snRNP core protein D1) (Sm-D IPI00302850 P62314 SNRPD1 2 autoantigen) SRRM2 (splicing coactivator subunit SRm300) (Serine/arginine repetitive matrix protein 2) (Serine/arginine-rich splicing factor-related nuclear matrix protein of 300 kDa) (Ser/Arg- related IPI00782992 Q9UQ35 SRRM2 2 nuclear matrix protein) (SR-related nuclear matrix protein of 300 kDa) (300 kDa nuclear matrix antigen) IPI00171903 P52272 HNRPM hnRNP M (Heterogeneous nuclear ribonucleoprotein M) 3 hnRNP K (Heterogeneous nuclear ribonucleoprotein K) (Transformation up-regulated nuclear IPI00216049 P61978 HNRPK 2 protein) (TUNP) Dyskerin (H/ACA ribonucleoprotein complex subunit 4) (Dyskerin) (Nopp140-associated protein of IPI00221394 O60832 DKC1 2 57 kDa) IPI00419373 P51991 HNRPA3 hnRNP A3 (Heterogeneous nuclear ribonucleoprotein A3) 3

Protein biosynthesis IPI00012079 P23588 EIF4B eIF-4B (Eukaryotic translation initiation factor 4B) 3 IPI00014424 Q05639 EEF1A2 eEF1A-2 (Elongation factor 1-alpha 2) (EF-1-alpha-2) (Elongation factor 1 A-2) (Statin S1) 3 Ribosomal protein L22 (60S ribosomal protein L22) (Epstein-Barr virus small RNA-associated IPI00219153 P35268 RPL22 3 protein) (EBER-associated protein) (EAP) (Heparin-binding protein HBp15) IPI00419880 P61247 RPS3A Ribosomal protein S3a (40S ribosomal protein S3a) 2 IPI00221093 P08708 RPS17 Ribosomal protein S17 (40S ribosomal protein S17) 2 IPI00179713 Q9Y6M1 IGF2BP2 IMP-2 (IGF-II mRNA-binding protein 2) (p62)(insulin-like growth factor 2 mRNA binding protein 2) 2

Cellular organization Cytoskeleton constituent proteins IPI00021428 P68133 ACTA1 Actin α-1 (Alpha actin 1) (Actin, alpha skeletal muscle) 7 Tubulin α-1 (Tubulin alpha-1 chain) (Alpha-tubulin 1) (Testis-specific alpha- tubulin) (Tubulin H2- IPI00007750 P68366 TUBA1 2 alpha) IPI00179709 Q13748 TUBA2 Tubulin α-2 (Tubulin alpha-2 chain) (Alpha-tubulin 2) 2 IPI00218343 Q9BQE3 TUBA6 Tubulin α-6 (Tubulin alpha-6 chain) (Alpha-tubulin 6) 3 IPI00011654 P07437 TUBB5 Tubulin β-5 (Tubulin beta chain) (Tubulin beta-5 chain) 4 IPI00418471 P08670 VIM Vimentin 4 IPI00013475 Q13885 TUBB2 Tubulin β-2A (Tubulin beta-2A chain) 2

Cytoskeleton accessory proteins Filamin A (Alpha-filamin) (Filamin-1) (Endothelial actin-binding protein) (Actin-binding protein 280) IPI00333541 P21333 FLNA 4 (ABP-280) (Nonmuscle filamin) IPI00026314 P06396 GSN Gelsolin (Actin-depolymerizing factor) (ADF) (Brevin) (AGEL) 3 IPI00008918 Q9UHB6 LIMA1 Eplin (Epithelial protein lost in neoplasm) (LIM domain and actin-binding protein 1) 3 IPI00166518 Q6WCQ1 RHOIP3 p116Rip (Myosin phosphatase-Rho interacting protein) (Rho-interacting protein 3) (M-RIP) (RIP3) 2 IPI00014516 Q05682 CALD1 Caldesmon (CDM) 2 IPI00008868 P46821 MAP1B MAP 1B (Microtubule-associated protein 1B) 2 IPI00413728 Q13813 SPTAN1 α-fodrin (Spectrin, non-erythroid alpha chain) (Alpha-II spectrin) (Fodrin alpha chain) 2 IPI00010779 P67936 TPM4 Tropomyosin 4 (Tropomyosin alpha-4 chain) (TM30p1) 2 IPI00433214 Q6NWZ1 CKAP4 CKAP4 protein (cytoskeleton-associated protein 4) 2

Motor proteins Myosin-9 (Myosin heavy chain, nonmuscle IIa) (Nonmuscle myosin heavy chain IIa) (NMMHC II-a) IPI00019502 P35579 MYH9 3 (NMMHC-IIA) (Cellular myosin heavy chain, type A) (Nonmuscle myosin heavy chain-A) (NMMHC- IPI00033494 Q13182 MRLC2 Myosin regulatory light chain (Myosin regulatory light chain MRLC2) (Nonmuscle myosin light chain 2) 2 IPI00166980 Q96GK3 KIF26A KIF26A (kinesin family member 26A) 2 IPI00025879 P12882 MYH1 Myosin-1 (Myosin heavy chain, skeletal muscle, adult 1) (Myosin heavy chain IIx/d) (MyHC-IIx/d) 2

Metabolic enzymes IPI00026781 P49327 FASN Fatty acid synthase 2 PK3 (Pyruvate kinase 3) (Pyruvate kinase M 2) (Pyruvate kinase isozymes M1/M2) (Pyruvate kinase IPI00383237 P14618 PKM2 3 muscle isozyme) (Pyruvate kinase 2/3) (Cytosolic thyroid hormone-binding protein) (CTHBP) IPI00376377 Q7Z789 DHRS2 Dehydrogenase/reductase SDR family member 2 (HEP27 protein) (Protein D) 2 IPI00440493 P25705 ATP5A1 ATP synthase, α (ATP synthase subunit alpha, mitochondrial precursor) 2 IPI00303476 P06576 ATP5B ATP synthase, β (ATP synthase subunit beta, mitochondrial precursor) 3 iPFK-2 (6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3) (6PF-2-K/Fru- 2,6-P2ASE IPI00004511 Q16875 PFKFB3 2 brain/placenta-type isozyme) (NY-REN-56 antigen) Protein disulfide-isomerase precursor (EC 5.3.4.1) (PDI) (Prolyl 4- hydroxylase subunit beta) IPI00010796 P07237 P4HB 2 (Cellular thyroid hormone-binding protein) (p55)

Chaperone and stress response IPI00003865 P11142 HSPA8 HSC70 (Heat shock cognate 71 kDa protein) (Heat shock 70 kDa protein 8) 4 IPI00382470 Q5CAQ7 HSPCA HSPCA (Heat shock protein HSP 90-alpha 2) 2 Ion channels CNG channel a 3 (Cyclic nucleotide-gated cation channel alpha 3) (CNG-3) (CNG3) (Cyclic nucleotide- IPI00000812 Q16281 CNGA3 2 gated channel alpha 3) (Cone photoreceptor cGMP-gated channel subunit alpha)

Miscellaneous Apoptosis BIP (78 kDa glucose-regulated protein precursor) (GRP 78) (Heat shock 70 kDa protein 5) IPI00003362 P11021 HSPA5 (Immunoglobulin heavy chain-binding protein) (BiP) (Endoplasmic reticulum lumenal Ca(2+)- 2 binding protein grp78) IPI00020012 P51693 APLP1 APLP (Amyloid-like protein 1 precursor) (APLP-1) 2 Mortalin 2 (Stress-70 protein, mitochondrial precursor) (75 kDa glucose-regulated protein) (GRP 75) IPI00007765 P38646 HSPA9B 2 (Peptide-binding protein 74) (PBP74) (Mortalin) (MOT) IPI00006079 Q9NYF8 BCLAF1 BTF (Bcl-2-associated transcription factor 1) (Btf) 3

Proteolysis and ubiquitination IPI00179330 Q5RKT7 RPS27A Ubiquitin and ribosomal protein S27a 3 IPI00719280 Q5U5U6 UBB Ubiquitin B 3 IPI00784990 Q5UGI3 UBC Ubiquitin C 2 IPI00456429 Q3MIH3 UBA52 CEP52 (Ubiquitin and ribosomal protein L40 precursor) (60S ribosomal protein L40) 3 IPI00009823 P15085 CPA1 Carboxypeptidase A1 2

Others IPI00010849 P05814 CSN2 β-casein (Casein beta) 2

Unknown IPI00012202 Q9BQA1 WDR77 Methylosome protein 50 4 IPI00003269 Hypothetical protein LOC345651 2 IPI00419322 Q7Z4V5 HDGF2 HDGF2 (Hepatoma-derived growth factor 2) (HGDF-related pro 2) 3 IPI00413922 11 kDa protein 2 IPI00550724 Similar to Actin, cytoplasmic 2 4 IPI00157721 46 kDa protein 4 IPI00444605 Q6ZSQ4 Hypothetical protein FLJ45296 3 IPI00455475 PREDICTED: similar to cytoskeletal β actin 2 PREDICTED: similar to FKSG30 (PREDICTED: similar to Prostate, ovary, testis expressed protein IPI00401614 4 on chromosome 2 ) IPI00385032 Q7Z3R3 Hypothetical protein DKFZp686J1593 2 IPI00248359 PREDICTED: similar to POTE2A 4 IPI00064328 Q96K27 Similar to SHK1 kinase-binding protein 1 3 IPI00397808 PREDICTED: similar to bA92K2.2 2