Huang Jing-Fei
Yunnan Key Laboratory of Molecular Biology of Domestic Animals, and the Key Laboratory of Cellular and Molecular Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, People's Republic of China.
Mol Biol Evol. 2003 May;20(5):815-20. doi: 10.1093/molbev/msg094. Epub 2003 Apr 2.
Protein tyrosine phosphatases (PTPs) are comprised of two superfamilies, the phosphatase I superfamily containing a single low-molecular-weight PTP (lmwPTP) family and the phosphatase II superfamily including both the higher-molecular-weight PTP (hmwPTP) and the dual-specificity phosphatase (DSP) families. The phosphatase I and II superfamilies are often considered to be the result of convergent evolution. The PTP sequence and structure analyses indicate that lmwPTPs, hmwPTPs, and DSPs share similar structures, functions, and a common signature motif, although they have low sequence identities and a different order of active sites in sequence or a circular permutation. The results of this work suggest that lmwPTPs and hmwPTPs/DSPs are remotely related in evolution. The earliest ancestral gene of PTPs could be from a short fragment containing about 90 approximately 120 nucleotides or 30 approximately 40 residues; however, a probable full PTP ancestral gene contained one transcript unit with two lmwPTP genes. All three PTP families may have resulted from a common ancestral gene by a series of duplications, fusions, and circular permutations. The circular permutation in PTPs is caused by a reading frame difference, which is similar to that in DNA methyltransferases. Nevertheless, the evolutionary mechanism of circular permutation in PTP genes seems to be more complicated than that in DNA methyltransferase genes. Both mechanisms in PTPs and DNA methyltransferases can be used to explain how some protein families and superfamilies came to be formed by circular permutations during molecular evolution.
蛋白质酪氨酸磷酸酶（PTPs）由两个超家族组成，磷酸酶I超家族包含一个低分子量PTP（lmwPTP）家族，磷酸酶II超家族包括高分子量PTP（hmwPTP）和双特异性磷酸酶（DSP）家族。磷酸酶I和II超家族通常被认为是趋同进化的结果。PTP序列和结构分析表明，lmwPTPs、hmwPTPs和DSPs具有相似的结构、功能和共同的特征基序，尽管它们的序列同一性较低，活性位点在序列中的顺序不同或存在环状排列。这项工作的结果表明，lmwPTPs与hmwPTPs/DSPs在进化上有较远的亲缘关系。PTPs最早的祖先基因可能来自一个约90至120个核苷酸或30至40个残基的短片段；然而，一个可能完整的PTP祖先基因包含一个转录单元和两个lmwPTP基因。所有三个PTP家族可能都源自一个共同的祖先基因，经过一系列的复制、融合和环状排列。PTPs中的环状排列是由阅读框差异引起的，这与DNA甲基转移酶中的情况相似。然而，PTP基因中环状排列的进化机制似乎比DNA甲基转移酶基因中的更为复杂。PTPs和DNA甲基转移酶中的这两种机制都可以用来解释在分子进化过程中一些蛋白质家族和超家族是如何通过环状排列形成的。
