0 14 Identification identification NN 15 17 of of IN 18 33 transcriptional transcriptional JJ 34 44 suppressor suppressor NN 45 53 proteins protein NNS 54 58 that that WDT 59 63 bind bind VBP 64 66 to to TO 67 70 the the DT 71 79 negative negative JJ 80 90 regulatory regulatory JJ 91 98 element element NN 99 101 of of IN 102 105 the the DT 106 111 human human JJ 112 128 immunodeficiency immunodeficiency NN 129 134 virus virus NN 135 139 type type NN 140 141 1 1 CD 141 142 . . . 144 147 Two two CD 148 157 different different JJ 158 166 proteins protein NNS 167 172 which which WDT 173 186 independently independently RB 187 192 bound bind VBD 193 195 to to TO 196 207 neighboring neighbor VBG 208 217 sequences sequence NNS 218 224 within within IN 225 228 the the DT 229 237 negative negative JJ 238 248 regulatory regulatory JJ 249 256 element element NN 257 258 ( ( ( 258 261 NRE NRE NNP 261 262 ) ) ) 263 265 of of IN 266 271 human human JJ 272 288 immunodeficiency immunodeficiency NN 289 294 virus virus NN 295 299 type type NN 300 301 1 1 CD 302 303 ( ( ( 303 308 HIV-1 HIV-1 NNP 308 309 ) ) ) 310 314 were be VBD 315 323 detected detect VBN 324 326 in in IN 327 330 the the DT 331 338 nuclear nuclear JJ 339 346 extract extract NN 347 349 of of IN 350 351 a a DT 352 366 virus-infected virus-infected JJ 367 372 human human JJ 373 374 T t NN 375 379 cell cell NN 380 384 line line NN 384 385 . . . 386 389 One one CD 390 392 of of IN 393 396 the the DT 397 404 factors factor NNS 405 410 bound bind VBD 411 413 to to TO 414 415 a a DT 416 421 novel novel JJ 422 426 dyad dyad NN 427 438 symmetrical symmetrical JJ 439 447 sequence sequence NN 447 448 . . . 449 453 This this DT 454 462 sequence sequence NN 463 465 is be VBZ 466 470 well well RB 471 480 conserved conserve VBN 481 483 in in IN 484 491 various various JJ 492 497 HIV-1 HIV-1 NNP 498 506 isolates isolate NNS 507 510 and and CC 511 518 partial partial JJ 519 527 homology homology NN 528 531 was be VBD 532 537 found find VBN 538 542 with with IN 543 546 the the DT 547 555 promoter promoter NN 556 562 region region NN 563 565 of of IN 566 569 the the DT 570 575 human human JJ 576 590 retinoblastoma retinoblastoma NN 591 595 gene gene NN 595 596 . . . 597 604 Similar similar JJ 605 608 DNA dna NN 609 616 binding binding NN 617 625 activity activity NN 626 629 was be VBD 630 638 detected detect VBN 639 641 in in IN 642 643 a a DT 644 651 variety variety NN 652 654 of of IN 655 671 virus-uninfected virus-uninfected JJ 672 677 human human JJ 678 679 T t NN 680 684 cell cell NN 685 690 lines line NNS 691 694 and and CC 695 699 HeLa HeLa NNP 700 705 cells cell NNS 706 708 by by IN 709 714 means mean NNS 715 717 of of IN 718 719 a a DT 720 723 gel gel NN 724 732 mobility mobility NN 733 738 shift shift NN 739 744 assay assay NN 744 745 . . . 746 749 The the DT 750 755 other other JJ 756 762 factor factor NN 763 768 bound bind VBN 769 771 to to TO 772 773 a a DT 774 782 putative putative JJ 783 787 AP-1 ap-1 NN 788 799 recognition recognition NN 800 808 sequence sequence NN 809 818 predicted predict VBN 819 822 for for IN 823 826 the the DT 827 832 HIV-1 HIV-1 NNP 833 836 NRE NRE NNP 836 837 . . . 838 845 However however RB 845 846 , , , 847 851 this this DT 852 858 factor factor NN 859 862 did do VBD 863 866 not not RB 867 871 bind bind VB 872 874 to to TO 875 876 a a DT 877 884 typical typical JJ 885 889 AP-1 ap-1 NN 890 894 site site NN 894 895 . . . 896 899 The the DT 900 909 insertion insertion NN 910 912 of of IN 913 921 multiple multiple JJ 922 928 copies copy NNS 929 931 of of IN 932 935 the the DT 936 943 binding bind VBG 944 948 site site NN 949 952 for for IN 953 956 the the DT 957 963 former former JJ 964 966 or or CC 967 973 latter latter JJ 974 980 factor factor NN 981 985 into into IN 986 987 a a DT 988 1000 heterologous heterologous JJ 1001 1009 promoter promoter NN 1010 1017 reduced reduce VBD 1018 1021 the the DT 1022 1030 promoter promoter NN 1031 1039 activity activity NN 1040 1042 to to TO 1043 1052 one-tenth one-tenth NN 1053 1055 or or CC 1056 1065 one-third one-third NN 1065 1066 , , , 1067 1079 respectively respectively RB 1079 1080 . . . 1081 1085 Thus thus RB 1085 1086 , , , 1087 1091 each each DT 1092 1098 factor factor NN 1099 1102 may may MD 1103 1111 function function VB 1112 1114 as as IN 1115 1116 a a DT 1117 1122 novel novel JJ 1123 1131 negative negative JJ 1132 1141 regulator regulator NN 1142 1144 of of IN 1145 1158 transcription transcription NN 1158 1159 . . .