Williams K R, Stone K L, LoPresti M B, Merrill B M, Planck S R
Proc Natl Acad Sci U S A. 1985 Sep;82(17):5666-70. doi: 10.1073/pnas.82.17.5666.
A complete amino acid sequence has been determined for the UP1 single-stranded DNA binding protein from calf thymus that was first described by G. Herrick and B. M. Alberts [(1976) J. Biol. Chem. 251, 2124-2132]. Peptides required to establish the UP1 sequence were isolated by reversed-phase HPLC of digests produced by endoproteinase Lys-C, trypsin, chymotrypsin, Staphylococcus aureus V8 protease, and cyanogen bromide cleavage of UP1. The purified peptides were coupled to aminopolystyrene prior to solid-phase sequencing. UP1 contains 195 amino acids and has a molecular weight of 22,162. UP1 has a blocked NH2 terminus and contains a single NG,NG-dimethylarginine residue near its COOH terminus. Gas-phase sequencing of tryptic peptides derived from an analogous protein from mouse myeloma cells [Planck, S. R. & Wilson, S. H. (1980) J. Biol. Chem. 255, 11547-11556] revealed that this mouse helix-destabilizing protein shares a high degree of sequence homology with UP1. Of the 59 amino acids in the mouse protein that have so far been found to be homologous with UP1, 48 correspond exactly to sequences found in UP1. Most of the 11 differences that have been found between the sequences of these two proteins are conservative in nature, involving primarily the interchange of chemically similar amino acids. One 9-residue mouse sequence that is not obviously homologous to UP1 may be a result of the larger size of the mouse myeloma protein as compared to UP1. Since none of the UP1 or mouse myeloma helix-destabilizing protein sequence appears to be homologous to that of any previously sequenced protein, we presume that these two proteins represent a distinct class of single-stranded nucleic acid binding proteins that probably play a role in metabolism of single-stranded RNA or DNA in vivo.
已确定来自小牛胸腺的UP1单链DNA结合蛋白的完整氨基酸序列，该蛋白最早由G.赫里克和B.M.艾伯茨描述[（1976年）《生物化学杂志》251卷，2124 - 2132页]。通过对UP1经内肽酶Lys - C、胰蛋白酶、糜蛋白酶、金黄色葡萄球菌V8蛋白酶消化以及溴化氰裂解产生的消化产物进行反相高效液相色谱法，分离出确定UP1序列所需的肽段。纯化后的肽段在进行固相测序之前与氨基聚苯乙烯偶联。UP1含有195个氨基酸，分子量为22,162。UP1的氨基末端被封闭，并且在其羧基末端附近含有一个单-NG,NG - 二甲基精氨酸残基。对来自小鼠骨髓瘤细胞的类似蛋白的胰蛋白酶肽段进行气相测序[普朗克，S.R.和威尔逊，S.H.（1980年）《生物化学杂志》255卷，11547 - 11556页]表明，这种小鼠解螺旋蛋白与UP1具有高度的序列同源性。在小鼠蛋白中迄今发现与UP1同源的59个氨基酸中，有48个与UP1中的序列完全对应。在这两种蛋白的序列之间发现的11个差异中，大多数在本质上是保守的，主要涉及化学性质相似的氨基酸的互换。一个与UP1没有明显同源性的9个残基的小鼠序列可能是由于小鼠骨髓瘤蛋白比UP1更大。由于UP1或小鼠骨髓瘤解螺旋蛋白的序列似乎都与任何先前测序的蛋白的序列不同源，我们推测这两种蛋白代表一类独特的单链核酸结合蛋白，它们可能在体内单链RNA或DNA的代谢中起作用。
