Rakowicz-Szulczynska E M, Koprowski H
Wistar Institute of Anatomy and Biology, Philadelphia, Pennsylvania 19104.
Arch Biochem Biophys. 1989 Jun;271(2):366-79. doi: 10.1016/0003-9861(89)90286-5.
Nuclear transport and chromatin binding of monoclonal antibody (MAb) ME491, directed against a cell surface glycoprotein, was tested in intact cells and in a cell-free system. After a 24-h incubation with 125I-MAb ME491, the chromatin of melanoma cells and of colorectal carcinoma cells contained approximately 10 and 20%, respectively, of the antibody in nondegraded form. 125I-MAb ME491 was bound to a 55-kDa chromatin protein and localized in two HincII-digested chromatin fragments. Taken up by the nucleus, MAb ME491 inhibited transcription of ribosomal RNA genes by 70%. Nuclear uptake of 125I-MAb ME491 was increased up to ninefold when cells were preincubated with puromycin or actinomycin D. Nuclear uptake of MAb ME491 in a cell-free system was inhibited by ME491 antigen newly synthesized in the cytoplasm. Binding of 125I-MAb ME491 to the newly synthesized ME491 antigen caused precipitation of polysome-bound ME491 mRNA. The effect of MAb ME491 on transcription is discussed.
针对一种细胞表面糖蛋白的单克隆抗体（MAb）ME491的核转运和染色质结合，在完整细胞和无细胞体系中进行了检测。用¹²⁵I-MAb ME491孵育24小时后，黑色素瘤细胞和结肠癌细胞的染色质中分别含有约10%和20%未降解形式的抗体。¹²⁵I-MAb ME491与一种55 kDa的染色质蛋白结合，并定位于两个经HincII酶切的染色质片段中。MAb ME491被细胞核摄取后，核糖体RNA基因的转录被抑制了70%。当细胞用嘌呤霉素或放线菌素D预孵育时，¹²⁵I-MAb ME491的核摄取增加了多达九倍。在无细胞体系中，MAb ME491的核摄取受到细胞质中新合成的ME491抗原的抑制。¹²⁵I-MAb ME491与新合成的ME491抗原的结合导致多核糖体结合的ME491 mRNA沉淀。文中讨论了MAb ME491对转录的影响。
