Valdez B C, Henning D, Le T V, Busch H
Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030.
Biochem Biophys Res Commun. 1995 Feb 15;207(2):485-91. doi: 10.1006/bbrc.1995.1214.
Ag-NOR proteins are silver-stainable proteins in the nucleolar organizer regions and are used to distinguish benign from malignant tumors. B23 and C23 are the two major Ag-NOR proteins. This study shows that only one of the two acidic clusters of B23 is responsible for its silver staining property. Fusion of this region of B23 (amino acids 161-188) to glutathione S-transferase produced an Ag-NOR positive fusion protein. The same result was obtained when amino acids 233-277 of C23 was fused with glutathione S-transferase. The aspartate residues, but not the glutamate residues, were found to be primarily responsible for the silver staining of the acidic clusters.
核仁组成区嗜银蛋白（Ag-NOR蛋白）是核仁组织区中可被银染色的蛋白质，用于区分良性肿瘤和恶性肿瘤。B23和C23是两种主要的Ag-NOR蛋白。本研究表明，B23的两个酸性簇中只有一个负责其银染特性。将B23的该区域（氨基酸161 - 188）与谷胱甘肽S-转移酶融合产生了一种Ag-NOR阳性融合蛋白。当C23的氨基酸233 - 277与谷胱甘肽S-转移酶融合时，也得到了相同的结果。发现天冬氨酸残基而非谷氨酸残基是酸性簇银染的主要原因。
