UniProt UniProt http://www.uniprot.org Spatial mapping of splicing factor complexes involved in exon and intron definition. Spatial mapping of splicing factor complexes involved in exon and intron definition. The Journal of cell biology 2008 imex curation Ellis JD., Llères D., Denegri M., Lamond AI., Cáceres JF. Source of U2AF1 taken from previous work of authors/contributing scientist PMID:1388271 as described in referenced citation PMID:16043505 Javier.Caceres@hgu.mrc.ac.uk 09-May-2019: Contacted by IntAct-Help. Only protein-protein interactions imex curation human-293t Homo sapiens 293 cells transformed with SV40 large T antigen 293t 293 cells expressing SV40 large T antigen. The original designation of this cell line was 293tsA1609neo. It is not in Cabri,ATCC or HyperCLDB. anti tag coip anti tag coimmunoprecipitation anti tag coip anti tag western anti tag western blot anti tag western Ellis JD., Llères D., Denegri M., Lamond AI., Cáceres JF. Source of U2AF1 taken from previous work of authors/contributing scientist PMID:1388271 as described in referenced citation PMID:16043505 Javier.Caceres@hgu.mrc.ac.uk Accepted 2018-JUL-17 AT 14:56 BST AT 14:56 BST by PPORRAS The Journal of cell biology 2008 Only protein-protein interactions imex curation imex curation Spatial mapping of splicing factor complexes involved in exon and intron definition. Spatial mapping of splicing factor complexes involved in exon and intron definition. The Journal of cell biology 2008 imex curation Ellis JD., Llères D., Denegri M., Lamond AI., Cáceres JF. Source of U2AF1 taken from previous work of authors/contributing scientist PMID:1388271 as described in referenced citation PMID:16043505 Javier.Caceres@hgu.mrc.ac.uk 09-May-2019: Contacted by IntAct-Help. Only protein-protein interactions imex curation human-hela Homo sapiens epitheloid cervix carcinoma cells Human hela Human epitheloid cervix carcinoma HeLa cells derivation: cervix; epithelial; adenocarcinoma ATCC no:CCL-2 fret fluorescent resonance energy transfer FRET RET FRET analysis FRET RET FRET analysis fret tag fluorescence tag visualisation by fluorescence tag fluorescence Ellis JD., Llères D., Denegri M., Lamond AI., Cáceres JF. Source of U2AF1 taken from previous work of authors/contributing scientist PMID:1388271 as described in referenced citation PMID:16043505 Javier.Caceres@hgu.mrc.ac.uk Accepted 2018-JUL-17 AT 14:56 BST AT 14:56 BST by PPORRAS The Journal of cell biology 2008 Only protein-protein interactions imex curation imex curation Spatial mapping of splicing factor complexes involved in exon and intron definition. Spatial mapping of splicing factor complexes involved in exon and intron definition. The Journal of cell biology 2008 imex curation Ellis JD., Llères D., Denegri M., Lamond AI., Cáceres JF. Source of U2AF1 taken from previous work of authors/contributing scientist PMID:1388271 as described in referenced citation PMID:16043505 Javier.Caceres@hgu.mrc.ac.uk 09-May-2019: Contacted by IntAct-Help. Only protein-protein interactions imex curation human-293t Homo sapiens 293 cells transformed with SV40 large T antigen 293t 293 cells expressing SV40 large T antigen. The original designation of this cell line was 293tsA1609neo. It is not in Cabri,ATCC or HyperCLDB. anti tag coip anti tag coimmunoprecipitation anti tag coip western blot western blot Immuno blot Immuno blot Ellis JD., Llères D., Denegri M., Lamond AI., Cáceres JF. Source of U2AF1 taken from previous work of authors/contributing scientist PMID:1388271 as described in referenced citation PMID:16043505 Javier.Caceres@hgu.mrc.ac.uk Accepted 2018-JUL-17 AT 14:56 BST AT 14:56 BST by PPORRAS The Journal of cell biology 2008 Only protein-protein interactions imex curation imex curation Spatial mapping of splicing factor complexes involved in exon and intron definition. Spatial mapping of splicing factor complexes involved in exon and intron definition. The Journal of cell biology 2008 imex curation Ellis JD., Llères D., Denegri M., Lamond AI., Cáceres JF. Source of U2AF1 taken from previous work of authors/contributing scientist PMID:1388271 as described in referenced citation PMID:16043505 Javier.Caceres@hgu.mrc.ac.uk 09-May-2019: Contacted by IntAct-Help. Only protein-protein interactions imex curation human-293t Homo sapiens 293 cells transformed with SV40 large T antigen 293t 293 cells expressing SV40 large T antigen. The original designation of this cell line was 293tsA1609neo. It is not in Cabri,ATCC or HyperCLDB. anti bait coip anti bait coimmunoprecipitation anti bait coip western blot western blot Immuno blot Immuno blot Ellis JD., Llères D., Denegri M., Lamond AI., Cáceres JF. Source of U2AF1 taken from previous work of authors/contributing scientist PMID:1388271 as described in referenced citation PMID:16043505 Javier.Caceres@hgu.mrc.ac.uk Accepted 2018-JUL-17 AT 14:56 BST AT 14:56 BST by PPORRAS The Journal of cell biology 2008 Only protein-protein interactions imex curation imex curation srsf2_human Serine/arginine-rich splicing factor 2 Splicing factor SC35 Splicing component, 35 kDa Protein PR264 SRSF2 SFRS2 Splicing factor, arginine/serine-rich 2 protein protein human Homo sapiens Human MSYGRPPPDVEGMTSLKVDNLTYRTSPDTLRRVFEKYGRVGDVYIPRDRYTKESRGFAFVRFHDKRDAEDAMDAMDGAVLDGRELRVQMARYGRPPDSHHSRRGPPPRRYGGGGYGRRSRSPRRRRRSRSRSRSRSRSRSRSRYSRSKSRSRTRSRSRSTSKSRSARRSKSKSSSVSRSRSRSRSRSRSRSPPPVSKRESKSRSRSKSPPKSPEEEGAVSS DIP protein Q01130 original sequence version: 169 68121AC4D35714FA srsf3_human Serine/arginine-rich splicing factor 3 Pre-mRNA-splicing factor SRP20 SRSF3 SRP20 SFRS3 Splicing factor, arginine/serine-rich 3 protein protein human Homo sapiens Human MHRDSCPLDCKVYVGNLGNNGNKTELERAFGYYGPLRSVWVARNPPGFAFVEFEDPRDAADAVRELDGRTLCGCRVRVELSNGEKRSRNRGPPPSWGRRPRDDYRRRSPPPRRRSPRRRSFSRSRSRSLSRDRRRERSLSRERNHKPSRSFSRSRSRSRSNERK DIP protein P84103 original sequence version: 125 02F0A5EE33FF28A0 srsf1_human Serine/arginine-rich splicing factor 1 SF2 SF2P33 OK/SW-cl.3 SRSF1 ASF pre-mRNA-splicing factor SF2, P33 subunit Alternative-splicing factor 1 SFRS1 Splicing factor, arginine/serine-rich 1 protein protein human Homo sapiens Human MSGGGVIRGPAGNNDCRIYVGNLPPDIRTKDIEDVFYKYGAIRDIDLKNRRGGPPFAFVEFEDPRDAEDAVYGRDGYDYDGYRLRVEFPRSGRGTGRGGGGGGGGGAPRGRYGPPSRRSENRVVVSGLPPSGSWQDLKDHMREAGDVCYADVYRDGTGVVEFVRKEDMTYAVRKLDNTKFRSHEGETAYIRVKVDGPRSPSYGRSRSRSRSRSRSRSRSNSRSRSYSPRRSRGSPRYSPRHSRSRSRT DIP protein Q07955 original sequence version: 191 DIP protein Q07955 original sequence version: 160 C28A0B2F112EA713 sarnp_human SAP domain-containing ribonucleoprotein HSPC316 Cytokine-induced protein of 29 kDa SARNP Proliferation-associated cytokine-inducible protein CIP29 HCC1 Nuclear protein Hcc-1 protein protein human Homo sapiens Human MATETVELHKLKLAELKQECLARGLETKGIKQDLIHRLQAYLEEHAEEEANEEDVLGDETEEEETKPIELPVKEEEPPEKTVDVAAEKKVVKITSEIPQTERMQKRAERFNVPVSLESKKAARAARFGISSVPTKGLSSDNKPMVNLDKLKERAQRFGLNVSSISRKSEDDEKLKKRKERFGIVTSSAGTGTTEDTEAKKRKRAERFGIA 96AFDD37EA328126 ru17_human U1 small nuclear ribonucleoprotein 70 kDa SNRNP70 RPU1 U1AP1 RNPU1Z SNRP70 protein protein human Homo sapiens Human MTQFLPPNLLALFAPRDPIPYLPPLEKLPHEKHHNQPYCGIAPYIREFEDPRDAPPPTRAETREERMERKRREKIERRQQEVETELKMWDPHNDPNAQGDAFKTLFVARVNYDTTESKLRREFEVYGPIKRIHMVYSKRSGKPRGYAFIEYEHERDMHSAYKHADGKKIDGRRVLVDVERGRTVKGWRPRRLGGGLGGTRRGGADVNIRHSGRDDTSRYDERPGPSPLPHRDRDRDRERERRERSRERDKERERRRSRSRDRRRRSRSRDKEERRRSRERSKDKDRDRKRRSSRSRERARRERERKEELRGGGGDMAEPSEAGDAPPDDGPPGELGPDGPDGPEEKGRDRDRERRRSHRSERERRRDRDRDRDRDREHKRGERGSERGRDEARGGGGGQDNGLEGLGNDSRDMYMESEGGDGYLAPENGYLMEAAPE DIP protein P08621 original sequence version: 92 DIP protein P08621 original sequence version: 152 DIP protein P08621-1 original sequence version: 191 F1020BF5C40CF97D u2af1_human Splicing factor U2AF 35 kDa subunit U2 auxiliary factor 35 kDa subunit U2 snRNP auxiliary factor small subunit U2AF1 U2AF35 U2AFBP U2 small nuclear RNA auxiliary factor 1 FP793 protein protein human Homo sapiens Human MAEYLASIFGTEKDKVNCSFYFKIGACRHGDRCSRLHNKPTFSQTIALLNIYRNPQNSSQSADGLRCAVSDVEMQEHYDEFFEEVFTEMEEKYGEVEEMNVCDNLGDHLVGNVYVKFRREEDAEKAVIDLNNRWFNGQPIHAELSPVTDFREACCRQYEMGECTRGGFCNFMHLKPISRELRRELYGRRRKKHRSRSRSRERRSRSRDRGRGGGGGGGGGGGGRERDRRRSRDRERSGRF 3DA130DCE0B953F6 u2af2_human Splicing factor U2AF 65 kDa subunit U2AF2 U2AF65 U2 snRNP auxiliary factor large subunit U2 auxiliary factor 65 kDa subunit protein protein human Homo sapiens Human MSDFDEFERQLNENKQERDKENRHRKRSHSRSRSRDRKRRSRSRDRRNRDQRSASRDRRRRSKPLTRGAKEEHGGLIRSPRHEKKKKVRKYWDVPPPGFEHITPMQYKAMQAAGQIPATALLPTMTPDGLAVTPTPVPVVGSQMTRQARRLYVGNIPFGITEEAMMDFFNAQMRLGGLTQAPGNPVLAVQINQDKNFAFLEFRSVDETTQAMAFDGIIFQGQSLKIRRPHDYQPLPGMSENPSVYVPGVVSTVVPDSAHKLFIGGLPNYLNDDQVKELLTSFGPLKAFNLVKDSATGLSKGYAFCEYVDINVTDQAIAGLNGMQLGDKKLLVQRASVGAKNATLVSPPSTINQTPVTLQVPGLMSSQVQMGGHPTEVLCLMNMVLPEELLDDEEYEEIVEDVRDECSKYGLVKSIEIPRPVDGVEVPGCGKIFVEFTSVFDCQKAMQGLTGRKFANRVVVTKYCDPDSYHRRDFW DIP protein P26368 original sequence version: 86 DIP protein P26368 original sequence version: 151 DIP protein P26368-1 original sequence version: 151 DIP protein P26368 original sequence version: 124 26AD271CD8FC6211 snrnp70-srsf1-1 4 7 unspecified role unspecified role prey prey living cell living cell physiological level physiological level endogenous level endogenous endogenous endogenous level 9 unspecified role unspecified role bait bait living cell living cell physiological level physiological level endogenous level endogenous endogenous endogenous level physical association physical association Fig. 1A Cell extracts that were immunoprecipitated with an antibody against U1 70K were probed with a monoclonal anti-SF2/ASF antibody. As shown in Fig. 1 A (compare lanes 2 and 3), U1 70K was able to pull down SF2/ASF independently of the presence of RNA. snrnp70-srsf1-2 2 7 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region eyfp enhanced yellow fluorescent protein tag eyfp undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 9 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region cfp tag cyan fluorescent protein tag CFP cyan fluorescent protein cyan fluorescent protein CFP cfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 1B-D Next, we used FRET acceptor photobleaching to study the interactions of SF2/ASF with U1 70K in living HeLa cells. snrnp70-srsf1-3 2 7 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region mcherry mcherry fluorescent protein tag mcherry undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 9 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region egfp tag enhanced green fluorescent protein tag enhanced green fluorescent protein EGFP enhanced green fluorescent protein EGFP egfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 2 Next, we used FRET acceptor photobleaching to study the interactions of SF2/ASF with U1 70K in living HeLa cells. Inhibition of transcription may result in the interactions between splicing factors being inhibited at nucleoplasmic sites of transcription and splicing. snrnp70-srsf1-4 3 7 unspecified role unspecified role prey prey living cell living cell physiological level physiological level endogenous level endogenous endogenous endogenous level 10 unspecified role unspecified role bait bait over-expressed over expressed level over-expressed living cell living cell region egfp tag enhanced green fluorescent protein tag enhanced green fluorescent protein EGFP enhanced green fluorescent protein EGFP egfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined physical association physical association Fig. 3A As shown in Fig. 3 A (lanes 3 and 4), EGFP-U2AF35 was able to pull down SF2/ASF independently of the presence of RNA. Interaction was RNA-independant u2af1-srsf1-1 2 7 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept physiological level physiological level endogenous level endogenous endogenous endogenous level region eyfp enhanced yellow fluorescent protein tag eyfp undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 10 unspecified role unspecified role fluorescence donor fluorescence donor living cell living cell physiological level physiological level endogenous level endogenous endogenous endogenous level region cfp tag cyan fluorescent protein tag CFP cyan fluorescent protein cyan fluorescent protein CFP cfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 3B FRET between ECFP-U2AF35 and EYFP-SF2/ASF was observed and this interaction was not prevented by DRB treatment (Fig. 3 B). srsf1-u2af1-1 2 7 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region mcherry mcherry fluorescent protein tag mcherry undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 10 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region egfp tag enhanced green fluorescent protein tag enhanced green fluorescent protein EGFP enhanced green fluorescent protein EGFP egfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 4 The pseudocolored images depicting the FRET efficiencies in continuous color demonstrated that mCherry-SF2/ASF interacts with EGFP-U2AF35 srsf2-snrnp70-1 2 5 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region eyfp enhanced yellow fluorescent protein tag eyfp undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 9 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region cfp tag cyan fluorescent protein tag CFP cyan fluorescent protein cyan fluorescent protein CFP cfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 5A srsf2-snrnp70-2 2 5 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region mcherry mcherry fluorescent protein tag mcherry undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 9 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region egfp tag enhanced green fluorescent protein tag enhanced green fluorescent protein EGFP enhanced green fluorescent protein EGFP egfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 5B u2af1-snrnp70-1 2 10 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region cfp tag cyan fluorescent protein tag CFP cyan fluorescent protein cyan fluorescent protein CFP cfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 5 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region eyfp enhanced yellow fluorescent protein tag eyfp undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 5A srsf3-snrnp70-1 2 6 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region eyfp enhanced yellow fluorescent protein tag eyfp undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 9 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region cfp tag cyan fluorescent protein tag CFP cyan fluorescent protein cyan fluorescent protein CFP cfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 5A Next, we used FRET acceptor photobleaching to study the interactions of SF2/ASF with U1 70K in living HeLa cells. srsf3-u2af1-1 2 6 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept living cell living cell physiological level physiological level endogenous level endogenous endogenous endogenous level region eyfp enhanced yellow fluorescent protein tag eyfp undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 10 unspecified role unspecified role fluorescence donor fluorescence donor living cell living cell physiological level physiological level endogenous level endogenous endogenous endogenous level region cfp tag cyan fluorescent protein tag CFP cyan fluorescent protein cyan fluorescent protein CFP cfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 5A Next, we used FRET acceptor photobleaching to study the interactions of SF2/ASF with U1 70K in living HeLa cells. u2af1-srsf2-1 2 10 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region egfp tag enhanced green fluorescent protein tag enhanced green fluorescent protein EGFP enhanced green fluorescent protein EGFP egfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 5 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region mcherry mcherry fluorescent protein tag mcherry undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 5C sarnp-u2af1-1 1 8 unspecified role unspecified role bait bait over-expressed over expressed level over-expressed living cell living cell region t7 tag t7 tag MASMTGGQQMG epitope tag MASMTGGQQMG epitope tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 10 unspecified role unspecified role prey prey over-expressed over expressed level over-expressed living cell living cell region egfp tag enhanced green fluorescent protein tag enhanced green fluorescent protein EGFP enhanced green fluorescent protein EGFP egfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined physical association physical association Fig. 6A First, EGFP-U2AF35 was shown to be capable of pulling down T7-tagged HCC1.4 in Co-IP assays performed in 293T cells (Fig. 6 A). sarnp-u2af2-1 4 11 unspecified role unspecified role prey prey living cell living cell physiological level physiological level endogenous level endogenous endogenous endogenous level 8 unspecified role unspecified role bait bait living cell living cell physiological level physiological level endogenous level endogenous endogenous endogenous level physical association physical association Fig. 6B u2af1-sarnp-1 2 10 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region eyfp enhanced yellow fluorescent protein tag eyfp undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 8 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region cfp tag cyan fluorescent protein tag CFP cyan fluorescent protein cyan fluorescent protein CFP cfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 5C sarnp-u2af2-2 2 11 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region eyfp enhanced yellow fluorescent protein tag eyfp undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 8 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region cfp tag cyan fluorescent protein tag CFP cyan fluorescent protein cyan fluorescent protein CFP cfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 5C sarnp-u2af1-2 2 10 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region mcherry mcherry fluorescent protein tag mcherry undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 8 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region egfp tag enhanced green fluorescent protein tag enhanced green fluorescent protein EGFP enhanced green fluorescent protein EGFP egfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 7A sarnp-u2af2-3 2 11 unspecified role unspecified role fluorescence accept fluorescence acceptor fluorescence accept over-expressed over expressed level over-expressed living cell living cell region mcherry mcherry fluorescent protein tag mcherry undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined 8 unspecified role unspecified role fluorescence donor fluorescence donor over-expressed over expressed level over-expressed living cell living cell region egfp tag enhanced green fluorescent protein tag enhanced green fluorescent protein EGFP enhanced green fluorescent protein EGFP egfp tag undetermined undetermined sequence position undetermined undetermined undetermined sequence position undetermined proximity proximity close-contact colocalization neighbourhood interaction Fig. 7A