Pham C T, Armstrong R J, Zimonjic D B, Popescu N C, Payan D G, Ley T J
Department of Internal Medicine, Washington University Medical School, St. Louis, Missouri 63110-1093, USA.
J Biol Chem. 1997 Apr 18;272(16):10695-703. doi: 10.1074/jbc.272.16.10695.
Dipeptidyl peptidase I (DPPI) is a lysosomal cysteine protease that catalyzes the sequential removal of dipeptides from the amino termini of various protein substrates. We have isolated a cDNA coding for murine DPPI from mouse thymus and spleen cDNA libraries. The deduced amino acid sequence codes for a protein of 462 amino acid residues; comparison of this deduced sequence with that of rat and human DPPI revealed 90.1% and 77.8% identity, respectively. Using DPPI cDNA, we obtained two BAC (Bacterial Artificial Chromosome) clones that contained the murine DPPI locus. The DPPI gene consists of seven exons and 6 introns, and spans approximately 20 kilobases. Using fluorescence in situ chromosome hybridization, we localized murine DPPI to chromosome 7D3-E1.1. We determined that DPPI protein is widely distributed in mouse tissues, although its relative abundance varies from tissue to tissue. In contrast to previous reports, we show here that DPPI mRNA and protein levels and enzymatic activity are unchanged during in vitro T cell activation, implying that this enzyme is not rate-limiting for granzyme processing.
二肽基肽酶I（DPPI）是一种溶酶体半胱氨酸蛋白酶，可催化从各种蛋白质底物的氨基末端顺序去除二肽。我们从小鼠胸腺和脾脏cDNA文库中分离出编码小鼠DPPI的cDNA。推导的氨基酸序列编码一个由462个氨基酸残基组成的蛋白质；将该推导序列与大鼠和人类DPPI的序列进行比较，分别显示出90.1%和77.8%的同一性。利用DPPI cDNA，我们获得了两个包含小鼠DPPI基因座的细菌人工染色体（BAC）克隆。DPPI基因由7个外显子和6个内含子组成，跨度约为20千碱基。利用荧光原位染色体杂交技术，我们将小鼠DPPI定位于7D3-E1.1染色体上。我们确定DPPI蛋白在小鼠组织中广泛分布，尽管其相对丰度因组织而异。与先前的报道相反，我们在此表明，在体外T细胞激活过程中，DPPI mRNA和蛋白水平以及酶活性没有变化，这意味着该酶对颗粒酶加工不是限速酶。
