0 7 Thyroid thyroid JJ 8 15 hormone hormone NN 16 25 receptors receptor NNS 26 30 form form VBP 31 39 distinct distinct JJ 40 47 nuclear nuclear JJ 48 65 protein-dependent protein-dependent JJ 66 69 and and CC 70 81 independent independent JJ 82 91 complexes complex NNS 92 96 with with IN 97 98 a a DT 99 106 thyroid thyroid NN 107 114 hormone hormone NN 115 123 response response NN 124 131 element element NN 131 132 . . . 134 136 We we PRP 137 141 have have VBP 142 150 examined examine VBN 151 154 the the DT 155 162 binding binding NN 163 165 of of IN 166 173 nuclear nuclear JJ 174 182 proteins protein NNS 183 186 and and CC 187 198 recombinant recombinant JJ 199 206 thyroid thyroid NN 207 214 hormone hormone NN 215 224 receptors receptor NNS 225 226 ( ( ( 226 229 TRs TR NNP 229 230 ) ) ) 231 233 to to TO 234 237 the the DT 238 249 palindromic palindromic JJ 250 257 thyroid thyroid NN 258 265 hormone hormone NN 266 276 responsive responsive JJ 277 284 element element NN 285 297 AGGTCATGACCT AGGTCATGACCT NNP 298 299 ( ( ( 299 303 TREp TREp NNP 303 304 ) ) ) 305 310 using use VBG 311 312 a a DT 313 316 gel gel NN 317 332 electrophoretic electrophoretic JJ 333 341 mobility mobility NN 342 347 shift shift NN 348 353 assay assay NN 353 354 . . . 355 359 Four four CD 360 368 specific specific JJ 369 380 protein-DNA protein-dna JJ 381 390 complexes complex NNS 391 395 were be VBD 396 404 detected detect VBN 405 410 after after IN 411 421 incubation incubation NN 422 424 of of IN 425 432 nuclear nuclear JJ 433 441 extracts extract NNS 442 443 ( ( ( 443 445 NE NE NNP 445 446 ) ) ) 447 451 from from IN 452 465 T3-responsive t3-responsive JJ 466 475 pituitary pituitary NN 476 477 ( ( ( 477 480 GH3 gh3 NN 480 481 ) ) ) 482 487 cells cell NNS 488 492 with with IN 493 494 a a DT 495 510 TREp-containing trep-containing JJ 511 514 DNA dna NN 515 523 fragment fragment NN 523 524 . . . 525 529 This this DT 530 533 was be VBD 534 542 compared compare VBN 543 547 with with IN 548 551 the the DT 552 556 TREp TREp NNP 557 564 binding binding NN 565 567 of of IN 568 580 reticulocyte reticulocyte NN 581 599 lysate-synthesized lysate-synthesized JJ 600 603 TRs tr NNS 603 604 . . . 605 607 TR TR NNP 608 613 alpha alpha NN 614 615 1 1 CD 616 619 and and CC 620 622 TR TR NNP 623 627 beta beta NN 628 629 2 2 CD 630 634 each each DT 635 641 formed form VBD 642 643 a a DT 644 650 single single JJ 651 656 major major JJ 657 664 TR:TREp tr:trep NN 665 672 complex complex NN 673 678 which which WDT 679 689 comigrated comigrate VBD 690 694 with with IN 695 698 the the DT 699 704 least least JJS 705 713 retarded retarded JJ 714 721 complex complex NN 722 728 formed form VBN 729 731 by by IN 732 735 GH3 GH3 NNP 736 738 NE NE NNP 738 739 , , , 740 745 while while IN 746 748 TR TR NNP 749 753 beta beta NN 754 755 1 1 CD 756 762 formed form VBD 763 771 multiple multiple JJ 772 781 complexes complex NNS 782 792 suggesting suggest VBG 793 797 that that IN 798 800 it it PRP 801 804 can can MD 805 809 bind bind VB 810 812 to to TO 813 817 TREp trep NN 818 820 as as IN 821 823 an an DT 824 832 oligomer oligomer NN 832 833 . . . 834 847 Interestingly interestingly RB 847 848 , , , 849 861 coincubation coincubation NN 862 864 of of IN 865 871 35S-TR 35S-TR NNP 872 877 alpha alpha NN 878 879 1 1 CD 879 880 , , , 881 884 GH3 GH3 NNP 885 887 NE NE NNP 887 888 , , , 889 892 and and CC 893 902 unlabeled unlabeled JJ 903 907 TREp trep NN 908 916 resulted result VBD 917 919 in in IN 920 923 not not RB 924 928 only only RB 929 932 the the DT 933 944 35S-TR:TREp 35s-tr:trep NN 945 952 complex complex NN 952 953 , , , 954 957 but but CC 958 960 in in IN 961 964 two two CD 965 975 additional additional JJ 976 980 more more RBR 981 988 greatly greatly RB 989 997 retarded retard VBN 998 1007 complexes complex NNS 1008 1018 containing contain VBG 1019 1025 35S-TR 35S-TR NNP 1026 1031 alpha alpha NN 1032 1033 1 1 CD 1034 1037 and and CC 1038 1049 comigrating comigrate VBG 1050 1054 with with IN 1055 1060 those those DT 1061 1067 formed form VBN 1068 1070 by by IN 1071 1074 GH3 GH3 NNP 1075 1082 extract extract NN 1083 1088 alone alone RB 1088 1089 . . . 1090 1100 Incubation Incubation NNP 1101 1103 of of IN 1104 1108 each each DT 1109 1111 of of IN 1112 1115 the the DT 1116 1119 TRs tr NNS 1120 1124 with with IN 1125 1127 NE NE NNP 1128 1132 from from IN 1133 1138 COS-7 cos-7 NN 1139 1144 cells cell NNS 1144 1145 , , , 1146 1151 which which WDT 1152 1154 do do VBP 1155 1158 not not RB 1159 1166 possess possess VB 1167 1177 sufficient sufficient JJ 1178 1188 endogenous endogenous JJ 1189 1192 TRs tr NNS 1193 1195 to to TO 1196 1203 mediate mediate VB 1204 1216 T3-responses t3-respons NNS 1216 1217 , , , 1218 1226 resulted result VBD 1227 1229 in in IN 1230 1239 formation formation NN 1240 1242 of of IN 1243 1244 a a DT 1245 1248 new new JJ 1248 1249 , , , 1250 1254 more more RBR 1255 1262 greatly greatly RB 1263 1270 shifted shift VBD 1271 1278 complex complex NN 1278 1279 . . . 1280 1281 A a DT 1282 1289 similar similar JJ 1289 1290 , , , 1291 1295 heat heat NN 1296 1302 labile labile NN 1303 1311 activity activity NN 1312 1317 which which WDT 1318 1325 altered alter VBD 1326 1334 mobility mobility NN 1335 1337 of of IN 1338 1341 the the DT 1342 1348 TR:TRE TR:TRE NNP 1349 1356 complex complex NN 1357 1360 was be VBD 1361 1365 also also RB 1366 1373 present present JJ 1374 1376 in in IN 1377 1379 NE NE NNP 1380 1384 from from IN 1385 1400 T3-unresponsive t3-unresponsive JJ 1401 1406 JEG-3 JEG-3 NNP 1407 1412 cells cell NNS 1412 1413 . . . 1414 1416 At at IN 1417 1421 high high JJ 1422 1435 concentration concentration NN 1436 1438 of of IN 1439 1441 NE NE NNP 1441 1442 , , , 1443 1446 all all DT 1447 1449 of of IN 1450 1453 the the DT 1454 1456 TR tr NN 1457 1462 bound bind VBD 1463 1465 to to TO 1466 1470 TREp trep NN 1471 1474 was be VBD 1475 1479 more more RBR 1480 1487 greatly greatly RB 1488 1496 retarded retard VBN 1497 1501 than than IN 1502 1504 in in IN 1505 1508 the the DT 1509 1516 absence absence NN 1517 1519 of of IN 1520 1522 NE NE NNP 1522 1523 . . . 1524 1534 Truncation Truncation NNP 1535 1537 of of IN 1538 1540 TR TR NNP 1541 1546 alpha alpha NN 1547 1548 1 1 CD 1549 1551 at at IN 1552 1557 amino amino JJ 1558 1562 acid acid NN 1563 1566 210 210 CD 1567 1576 prevented prevent VBD 1577 1587 additional additional JJ 1588 1595 complex complex NN 1596 1605 formation formation NN 1606 1608 in in IN 1609 1612 the the DT 1613 1621 presence presence NN 1622 1624 of of IN 1625 1627 NE NE NNP 1628 1635 without without IN 1636 1645 affecting affect VBG 1646 1649 DNA dna NN 1650 1657 binding binding NN 1657 1658 , , , 1659 1669 suggesting suggest VBG 1670 1674 that that IN 1675 1678 the the DT 1679 1696 carboxyl-terminus carboxyl-terminus NN 1697 1699 of of IN 1700 1703 the the DT 1704 1707 TRs TR NNP 1708 1710 is be VBZ 1711 1720 essential essential JJ 1721 1724 for for IN 1725 1736 interaction interaction NN 1737 1741 with with IN 1742 1749 nuclear nuclear JJ 1750 1758 proteins protein NNS 1758 1759 . . . 1760 1761 ( ( ( 1761 1769 ABSTRACT abstract NN 1770 1779 TRUNCATED truncated VBN 1780 1782 AT at IN 1783 1786 250 250 CD 1787 1792 WORDS words NNS 1792 1793 ) ) )