Murine plasma cell antigen PC-1 has a region homologous to the active site of bovine intestinal 5'-nucleotide phosphodiesterase I (EC 3.1.4.1).
Murine plasma cell antigen PC-1 has a region homologous to the active site of bovine intestinal 5'-nucleotide phosphodiesterase I (EC 3.1.4.1).
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鼠浆细胞抗原PC-1具有与牛肠5-核苷酸磷酸二酯酶I (EC 3.1.4.1)的活性位点同源的区域。
DOI：
10.1093/nar/19.21.6049
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发表时间：
1991
影响因子：
14.9
通讯作者：
M. Skinner
中科院分区：
文献类型：
--
作者：
M. Skinner
浆细胞抗原PC-1是一种表面抗原，其生理作用未知，在B细胞分化的晚期表达。该蛋白质是分子量为115000的单体的二硫键键同二聚体（1）。PC-1被预测为II类膜蛋白，具有24个氨基酸的氨基末端胞质结构域、21个氨基酸的跨膜结构域和826-828个氨基酸的胞外结构域（2，3）。该蛋白质在浆细胞和一些非淋巴组织中表达，即软骨细胞、唾液腺导管、附睾、输精管、肾远曲小管和脑毛细血管（4）。显示出约80%氨基酸同一性的人和鼠蛋白质在邻近跨膜区段的胞外区中具有两个拷贝的生长调节蛋白B结构域（5，6）。在残基479和504之间是ATP结合位点（7），在残基750周围存在钙结合蛋白中发现的EF-手状基序（3，8）。我已经观察到PC-1与来自牛肠磷酸二酯酶I（PPD 1，EC 3.1）的61个氨基酸的溴化氰肽具有高度同源性的区域。4.1)包括活性位点（9）。两个PC-1蛋白序列与磷酸二酯酶序列显示出74%的同一性，而在相同的序列上，两个PC-1序列的同一性为97%（图1）。PC-1和PPDI之间的同源性以前没有描述过，但最近已经报道（10）纯化的鼠PC-1蛋白具有磷酸二酯酶I活性。大鼠肠核苷酸焦磷酸酶（EC 3.6. 1.9)也有报道具有磷酸二酯酶I活性（11）。最近，来自牛肝的苏氨酸特异性蛋白激酶的16个肽片段显示与PC-1具有80-100%的同源性（7）。与人和鼠PC-1一样，这种推测的牛PC-1在残基210处具有丝氨酸，不像PPD 1具有苏氨酸。鉴于PC-1在鼠肠中缺乏表达（4），因此PPD 1不太可能代表牛PC-1。4.1)在数据库中，来自噬菌体T5的基因D15（12，NBRF NCBPT 5，在Swiss-Prot中也作为Exo $bpt 5，一种5 ′核酸外切酶，EC 3.1。11.3），显示与PC-1或PPD 1无显著同源性（酵母磷酸二酯酶，NBRF A26649是cAMP磷酸二酯酶，因此应为EC 3.1。4.17）。然而，D15苏氨酸118周围的序列与PPD 1的活性位点苏氨酸39周围的序列的同源性有限，特别是三肽TFP中苏氨酸残基的存在。使用SCRUTINEER程序（13）搜索图2所示基序的数据库，
Plasma cell antigen PC-1 is a surface antigen, the physiological role of which is unknown, expressed at a late stage of B-cell differentiation. The protein is a disulphide-bonded homodimer of a monomer with molecular weight 115000 (1). PC-1 is predicted to be a class II membrane protein with an aminoterminal cytoplasmic domain of 24 amino acids, a transmembrane domain of 21 amino acids and an extracellular domain of 826-828 amino acids (2, 3). The protein is expressed in plasma cells and in some non-lymphoid tissues, namely chondrocytes, salivary gland ducts, epididymis, vas deferens, the distal convoluted tubule of the kidney and in brain capillaries (4). Both human and murine proteins, which show about 80% amino acid identity, have two copies of the somatomedin B domain in the extracellular region adjacent to the transmembrane segment (5, 6). Between residues 479 and 504 is an ATP-binding site (7) and around residue 750 there is an EF-hand motif found in calcium-binding proteins (3, 8). I have observed that PC-1 has a region of high homology to a 61 amino acid cyanogen bromide peptide from bovineintestinal phosphodiesterase I (PPD1, EC 3.1. 4.1) including the active site (9). Both PC-1 protein sequences showed 74% identity to the phosphodiesterase sequence whereas, over the same sequence, the two PC-1 sequences were 97% identical (Figure1). The homology between PC-1 and PPDI has not been described previously, but recently it has been reported (10) that purified murine PC-1 protein has phosphodiesterase I activity. Rat intestinal nucleotide pyrophosphatase (EC 3.6. 1.9) has also been reported to have phosphodiesterase I activity (11). Recently, 16 peptide fragments ofa threonine-specific protein kinase from bovine liver were shown to have 80-100% homology to PC-1 (7). Like human and murine PC-1, this presumed bovine PC-I has a serine at residue 210, unlike PPD1 which has a threonine. Given the lack of expression of PC-I in the murine intestine (4) it is therefore unlikely that PPD1 represents bovine PC-1.The only other example of phosphodiesterase I (EC 3.1. 4.1) in the databases, gene D15from bacteriophage T5 (12, NBRF NCBPT5, also in Swiss-Prot as Exo $ bpt5, a 5'exonuclease, EC 3.1. 11.3), shows no significant homology to PC-1 or PPD1 (Yeast phosphodiesterase, NBRF A26649, is a cAMP phosphodiesterase and should therefore be EC 3.1. 4.17). There is, however, limited homology of the sequence around D15 threonine 118 with the sequence around the active sitethreonine 39 of PPD1, in particular the presence of the threonine residue in the tri-peptide TFP. A search of the databases for the motif shown in Figure 2, using the SCRUTINEER program (13),