Kumar A, Williams K R, Szer W
J Biol Chem. 1986 Aug 25;261(24):11266-73.
Protein A1 (Mr approximately 32,000), a major glycine-rich protein of heterogeneous nuclear ribonucleoproteins (hnRNP), was purified to near homogeneity under nondenaturing conditions from HeLa cells. Limited proteolysis of the native protein yields a trypsin-resistant N-terminal nucleic acid-binding domain about 195 amino acids long which has a primary structure nearly identical to that of the 195-amino acid-long single-stranded DNA (ssDNA)-binding protein UP1 (Mr 22,162) from calf thymus (Williams, K.R., Stone, K. L., LoPresti, M.B., Merrill, B. M., and Planck, S.R. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 5666-5670). 45 of the 61 glycine residues of A1 are present in the trypsin-sensitive C-terminal domain of the protein which contains no sequences homologous to UP1. Protein A2, another major glycine-rich core hnRNP protein from HeLa, has a domain structure analogous to A1 and appears to be related to ssDNA-binding proteins UP1-B from calf liver and HDP-1 from mouse myeloma in a way similar to the A1/UP1 relationship. In contrast to ssDNA-binding proteins, A1 binds preferentially to RNA over ssDNA and exhibits no helix-destabilizing activity.
蛋白质A1（分子量约32,000）是异质性核核糖核蛋白（hnRNP）中一种主要的富含甘氨酸的蛋白质，在非变性条件下从HeLa细胞中纯化至接近均一状态。对天然蛋白质进行有限的蛋白酶解产生一个约195个氨基酸长的对胰蛋白酶有抗性的N端核酸结合结构域，其一级结构与来自小牛胸腺的195个氨基酸长的单链DNA（ssDNA）结合蛋白UP1（分子量22,162）几乎相同（威廉姆斯，K.R.，斯通，K.L.，洛普雷蒂，M.B.，梅里尔，B.M.，和普朗克，S.R.（1985年）《美国国家科学院院刊》82，5666 - 5670）。A1的61个甘氨酸残基中有45个存在于该蛋白质对胰蛋白酶敏感的C端结构域中，该结构域不包含与UP1同源的序列。蛋白质A2是HeLa细胞中另一种主要的富含甘氨酸的核心hnRNP蛋白，其结构域结构与A1类似，并且似乎以类似于A1/UP1关系的方式与来自小牛肝脏的ssDNA结合蛋白UP1 - B和来自小鼠骨髓瘤的HDP - 1相关。与ssDNA结合蛋白不同，A1优先结合RNA而非ssDNA，并且不表现出螺旋解稳定活性。
