Jackson S P, Tjian R
Howard Hughes Medical Institute, Department of Biochemistry, University of California, Berkeley 94720.
Cell. 1988 Oct 7;55(1):125-33. doi: 10.1016/0092-8674(88)90015-3.
Glycosylation is often regarded as being restricted to proteins confined to the cell surface or within the lumen of intracellular organelles. Here we show that the human RNA polymerase II transcription factor Sp1 bears multiple O-linked N-acetylglucosamine (GlcNAc) monosaccharide residues. The lectin wheat germ agglutinin specifically inhibits the transcriptional activation but not the DNA binding function of Sp1. Furthermore, many other RNA polymerase II transcription factors also bear terminal GlcNAc residues, whereas most nuclear proteins, including RNA polymerase I and III transcription factors tested, do not. In some cases, only a subset of the polypeptide species within a particular family of closely related RNA polymerase II factors appears to be glycosylated. Our findings raise the possibility that O-linked GlcNAc residues play a role in the mechanism or regulation of transcriptional activation of RNA polymerase II.
糖基化通常被认为仅限于存在于细胞表面或细胞内细胞器腔中的蛋白质。在此我们表明，人类RNA聚合酶II转录因子Sp1带有多个O-连接的N-乙酰葡糖胺（GlcNAc）单糖残基。凝集素麦胚凝集素特异性抑制Sp1的转录激活，但不抑制其DNA结合功能。此外，许多其他RNA聚合酶II转录因子也带有末端GlcNAc残基，而大多数核蛋白，包括所测试的RNA聚合酶I和III转录因子，则没有。在某些情况下，特定家族中密切相关的RNA聚合酶II因子内只有一部分多肽种类似乎发生了糖基化。我们的发现增加了O-连接的GlcNAc残基在RNA聚合酶II转录激活机制或调控中发挥作用的可能性。
