0 13 CIITA-induced ciita-induced JJ 14 24 occupation occupation NN 25 27 of of IN 28 31 MHC MHC NNP 32 37 class class NN 38 40 II ii CD 41 50 promoters promoter NNS 51 53 is be VBZ 54 65 independent independent JJ 66 68 of of IN 69 72 the the DT 73 84 cooperative cooperative JJ 85 98 stabilization stabilization NN 99 101 of of IN 102 105 the the DT 106 120 promoter-bound promoter-bound JJ 121 134 multi-protein multi-protein JJ 135 144 complexes complex NNS 144 145 . . . 147 154 Precise precise JJ 155 165 regulation regulation NN 166 168 of of IN 169 172 MHC MHC NNP 173 178 class class NN 179 181 II ii CD 182 192 expression expression NN 193 198 plays play VBZ 199 200 a a DT 201 208 crucial crucial JJ 209 213 role role NN 214 216 in in IN 217 220 the the DT 221 228 control control NN 229 231 of of IN 232 235 the the DT 236 242 immune immune JJ 243 251 response response NN 251 252 . . . 253 256 The the DT 257 271 transactivator transactivator NN 272 277 CIITA CIITA NNP 278 285 behaves behave VBZ 286 288 as as IN 289 290 a a DT 291 297 master master NN 298 308 controller controller NN 309 311 of of IN 312 324 constitutive constitutive JJ 325 328 and and CC 329 338 inducible inducible JJ 339 342 MHC MHC NNP 343 348 class class NN 349 351 II ii CD 352 356 gene gene NN 357 367 activation activation NN 367 368 , , , 369 372 but but CC 373 376 its its PRP$ 377 382 exact exact JJ 383 392 mechanism mechanism NN 393 395 of of IN 396 402 action action NN 403 405 is be VBZ 406 409 not not RB 410 415 known know VBN 415 416 . . . 417 427 Activation Activation NNP 428 430 of of IN 431 434 MHC MHC NNP 435 440 class class NN 441 443 II ii CD 444 453 promoters promoter NNS 454 462 requires require VBZ 463 470 binding binding NN 471 473 of of IN 474 476 at at IN 477 482 least least JJS 483 488 three three CD 489 497 distinct distinct JJ 498 511 multi-protein multi-protein JJ 512 521 complexes complex NNS 522 523 ( ( ( 523 526 RFX RFX NNP 526 527 , , , 528 532 X2BP X2BP NNP 533 536 and and CC 537 541 NF-Y NF-Y NNP 541 542 ) ) ) 542 543 . . . 544 546 It it PRP 547 549 is be VBZ 550 555 known know VBN 556 560 that that IN 561 564 the the DT 565 574 stability stability NN 575 577 of of IN 578 582 this this DT 583 590 binding binding NN 591 598 results result VBZ 599 603 from from IN 604 615 cooperative cooperative JJ 616 628 interactions interaction NNS 629 636 between between IN 637 642 these these DT 643 651 proteins protein NNS 651 652 . . . 653 655 We we PRP 656 660 show show VBP 661 665 here here RB 666 670 that that IN 671 681 expression expression NN 682 684 of of IN 685 690 CIITA CIITA NNP 691 693 in in IN 694 697 MHC MHC NNP 698 703 class class NN 704 707 II- ii- NN 708 713 cells cell NNS 714 722 triggers trigger VBZ 723 733 occupation occupation NN 734 736 of of IN 737 740 the the DT 741 750 promoters promoter NNS 751 753 by by IN 754 759 these these DT 760 769 complexes complex NNS 769 770 . . . 771 775 This this DT 776 787 observation observation NN 788 794 raised raise VBD 795 798 the the DT 799 810 possibility possibility NN 811 815 that that IN 816 819 the the DT 820 826 effect effect NN 827 829 of of IN 830 835 CIITA CIITA NNP 836 838 on on IN 839 847 promoter promoter NN 848 858 occupation occupation NN 859 861 is be VBZ 862 870 mediated mediate VBN 871 873 by by IN 874 876 an an DT 877 883 effect effect NN 884 886 on on IN 887 890 the the DT 891 902 cooperative cooperative JJ 903 916 stabilization stabilization NN 917 919 of of IN 920 923 the the DT 924 933 DNA-bound dna-bound JJ 934 947 multi-protein multi-protein JJ 948 957 complexes complex NNS 957 958 . . . 959 961 We we PRP 962 966 show show VBP 966 967 , , , 968 975 however however RB 975 976 , , , 977 981 that that IN 982 985 the the DT 986 994 presence presence NN 995 997 of of IN 998 1003 CIITA CIITA NNP 1004 1008 does do VBZ 1009 1012 not not RB 1013 1019 affect affect VB 1020 1023 the the DT 1024 1033 stability stability NN 1034 1036 of of IN 1037 1040 the the DT 1041 1053 higher-order higher-ord JJR 1054 1061 protein protein NN 1062 1069 complex complex NN 1070 1076 formed form VBN 1077 1079 on on IN 1080 1083 DNA DNA NNP 1084 1086 by by IN 1087 1090 RFX RFX NNP 1090 1091 , , , 1092 1096 X2BP X2BP NNP 1097 1100 and and CC 1101 1105 NF-Y NF-Y NNP 1105 1106 . . . 1107 1111 This this DT 1112 1120 suggests suggest VBZ 1121 1126 other other JJ 1127 1137 mechanisms mechanism NNS 1138 1141 for for IN 1142 1155 CIITA-induced ciita-induced JJ 1156 1164 promoter promoter NN 1165 1174 occupancy occupancy NN 1174 1175 , , , 1176 1180 such such JJ 1181 1183 as as IN 1184 1186 an an DT 1187 1193 effect effect NN 1194 1196 on on IN 1197 1206 chromatin chromatin NN 1207 1216 structure structure NN 1217 1224 leading lead VBG 1225 1227 to to TO 1228 1237 increased increase VBN 1238 1251 accessibility accessibility NN 1252 1254 of of IN 1255 1258 MHC MHC NNP 1259 1264 class class NN 1265 1267 II ii CD 1268 1277 promoters promoter NNS 1277 1278 . . . 1279 1283 This this DT 1284 1291 ability ability NN 1292 1294 of of IN 1295 1300 CIITA CIITA NNP 1301 1303 to to TO 1304 1314 facilitate facilitate VB 1315 1323 promoter promoter NN 1324 1334 occupation occupation NN 1335 1337 is be VBZ 1338 1351 undissociable undissociable JJ 1352 1356 from from IN 1357 1360 its its PRP$ 1361 1376 transactivation transactivation NN 1377 1386 potential potential NN 1386 1387 . . . 1388 1395 Finally finally RB 1395 1396 , , , 1397 1399 we we PRP 1400 1408 conclude conclude VBP 1409 1413 that that IN 1414 1418 this this DT 1419 1425 effect effect NN 1426 1428 of of IN 1429 1434 CIITA CIITA NNP 1435 1437 is be VBZ 1438 1447 cell-type cell-type JJ 1448 1456 specific specific JJ 1456 1457 , , , 1458 1463 since since IN 1464 1474 expression expression NN 1475 1477 of of IN 1478 1483 CIITA CIITA NNP 1484 1486 is be VBZ 1487 1490 not not RB 1491 1499 required require VBN 1500 1503 for for IN 1504 1510 normal normal JJ 1511 1521 occupation occupation NN 1522 1524 of of IN 1525 1528 MHC MHC NNP 1529 1534 class class NN 1535 1537 II ii CD 1538 1547 promoters promoter NNS 1548 1550 in in IN 1551 1552 B B NNP 1553 1564 lymphocytes lymphocyte NNS 1564 1565 . . .