0 14 Preassociation Preassociation NNP 15 17 of of IN 18 23 STAT1 STAT1 NNP 24 28 with with IN 29 34 STAT2 STAT2 NNP 35 38 and and CC 39 44 STAT3 stat3 NN 45 47 in in IN 48 56 separate separate JJ 57 67 signalling signalling NN 68 77 complexes complex NNS 78 83 prior prior RB 84 86 to to TO 87 95 cytokine cytokine NN 96 107 stimulation stimulation NN 107 108 . . . 110 111 A a DT 112 119 variety variety NN 120 122 of of IN 123 132 cytokines cytokine NNS 133 136 and and CC 137 143 growth growth NN 144 151 factors factor NNS 152 155 act act VBP 156 163 through through IN 164 166 an an DT 167 176 induction induction NN 177 179 of of IN 180 184 gene gene NN 185 195 expression expression NN 196 204 mediated mediate VBN 205 207 by by IN 208 209 a a DT 210 216 family family NN 217 219 of of IN 220 226 latent latent JJ 227 240 transcription transcription NN 241 248 factors factor NNS 249 255 called call VBN 256 260 STAT STAT NNP 261 262 ( ( ( 262 268 signal signal NN 269 280 transducers transducer NNS 281 284 and and CC 285 295 activators activator NNS 296 298 of of IN 299 312 transcription transcription NN 312 313 ) ) ) 314 322 proteins protein NNS 322 323 . . . 324 338 Ligand-induced ligand-induced JJ 339 347 tyrosine tyrosine NN 348 363 phosphorylation phosphorylation NN 364 366 of of IN 367 370 the the DT 371 376 STATs STAT NNP 377 385 promotes promote VBZ 386 391 their their PRP$ 392 401 homodimer homodimer NN 402 405 and and CC 406 417 heterodimer heterodimer NN 418 427 formation formation NN 428 431 and and CC 432 442 subsequent subsequent JJ 443 450 nuclear nuclear JJ 451 464 translocation translocation NN 464 465 . . . 466 468 We we PRP 469 480 demonstrate demonstrate VBP 481 485 here here RB 486 490 that that IN 491 495 STAT stat NN 496 503 protein protein NN 504 519 heterocomplexes heterocomplex NNS 520 525 exist exist VBP 526 531 prior prior RB 532 534 to to TO 535 543 cytokine cytokine NN 544 553 treatment treatment NN 553 554 . . . 555 559 When when WRB 560 572 unstimulated unstimulated JJ 573 577 HeLa HeLa NNP 578 583 cells cell NNS 584 587 are be VBP 588 596 ruptured rupture VBN 597 599 in in IN 600 609 hypotonic hypotonic JJ 610 616 buffer buffer NN 617 624 without without IN 625 629 salt salt NN 630 632 or or CC 633 642 detergent detergent NN 642 643 , , , 644 660 immunoadsorption immunoadsorption NN 661 663 of of IN 664 670 either either CC 671 676 STAT1 stat1 NN 677 679 or or CC 680 685 STAT2 stat2 NN 686 690 from from IN 691 694 the the DT 695 704 resulting result VBG 705 712 cytosol cytosol NN 713 719 yields yield VBZ 720 738 coimmunoadsorption coimmunoadsorption NN 739 741 of of IN 742 745 the the DT 746 751 other other JJ 752 756 STAT stat NN 757 764 protein protein NN 764 765 . . . 766 775 Similarly similarly RB 775 776 , , , 777 788 STAT1-STAT3 stat1-stat3 NN 789 804 heterocomplexes heterocomplex NNS 805 808 are be VBP 809 825 coimmunoadsorbed coimmunoadsorbe VBN 826 830 from from IN 831 840 hypotonic hypotonic JJ 841 848 cytosol cytosol NN 848 849 . . . 850 855 STAT1 STAT1 NNP 856 859 and and CC 860 865 STAT2 STAT2 NNP 866 868 or or CC 869 874 STAT1 STAT1 NNP 875 878 and and CC 879 884 STAT3 STAT3 NNP 885 895 translated translate VBN 896 898 in in IN 899 911 reticulocyte reticulocyte NN 912 918 lysate lysate NN 919 932 spontaneously spontaneously RB 933 937 form form VBP 938 953 heterocomplexes heterocomplex NNS 954 958 when when WRB 959 962 the the DT 963 974 translation translation NN 975 982 lysates lysate NNS 983 986 are be VBP 987 992 mixed mix VBN 993 995 at at IN 996 997 0 0 CD 998 1005 degrees degree NNS 1006 1007 C c JJ 1007 1008 . . . 1009 1012 Our our PRP$ 1013 1017 data datum NNS 1018 1025 suggest suggest VBP 1026 1030 that that IN 1031 1047 interferon-alpha interferon-alpha NN 1048 1061 /beta-induced /beta-induced JJ 1062 1070 tyrosine tyrosine NN 1071 1086 phosphorylation phosphorylation NN 1087 1096 increases increase VBZ 1097 1100 the the DT 1101 1110 stability stability NN 1111 1113 of of IN 1114 1115 a a DT 1116 1127 preexisting preexisting JJ 1127 1128 , , , 1129 1135 latent latent JJ 1135 1136 , , , 1137 1148 STAT1-STAT2 stat1-stat2 NN 1149 1158 signaling signaling NN 1159 1166 complex complex NN 1166 1167 . . . 1168 1173 Newly newly RB 1174 1184 translated translate VBN 1185 1190 STAT1 stat1 NN 1191 1196 binds bind VBZ 1197 1199 in in IN 1200 1211 equilibrium equilibrium NN 1212 1219 fashion fashion NN 1220 1222 to to TO 1223 1228 STAT2 STAT2 NNP 1229 1232 and and CC 1233 1238 STAT3 STAT3 NNP 1238 1239 , , , 1240 1243 but but CC 1244 1246 we we PRP 1247 1251 show show VBP 1252 1256 that that IN 1257 1262 STAT2 stat2 NN 1263 1266 and and CC 1267 1272 STAT3 STAT3 NNP 1273 1278 exist exist VBP 1279 1281 in in IN 1282 1290 separate separate JJ 1291 1306 heterocomplexes heterocomplex NNS 1307 1311 with with IN 1312 1317 STAT1 stat1 NN 1317 1318 , , , 1319 1329 consistent consistent JJ 1330 1334 with with IN 1335 1336 a a DT 1337 1342 model model NN 1343 1345 in in IN 1346 1351 which which WDT 1352 1357 STAT1 STAT1 NNP 1358 1366 contains contain VBZ 1367 1368 a a DT 1369 1375 common common JJ 1376 1383 binding bind VBG 1384 1388 site site NN 1389 1392 for for IN 1393 1398 other other JJ 1399 1403 STAT stat NN 1404 1412 proteins protein NNS 1412 1413 . . .