Inokuchi N, Saitoh S, Kobayashi H, Itagaki T, Koyama T, Uchiyama S, Iwama M, Ohgi K, Irie M
Department of Microbiology, College of Pharmacy, Nihon University, Funabashi, Chiba, 274-0063, Japan.
J Biochem. 1998 Oct;124(4):848-56. doi: 10.1093/oxfordjournals.jbchem.a022189.
A base non-specific and acid RNase was isolated from cellular slime mold (Dictyostelium discoideum) cells in a homogeneous state (about 2.4 kDa) by SDS-polyacrylamide gel electrophoresis. The RNase (RNase DdI) has a pH optimum of 5.0. The amino acid sequence of RNase DdI was determined by a combination of protein chemistry, a search of Data base, Dicty cDB and further sequence analysis of cDNA from the same bank. RNase DdI consists of 198 amino acid residues, and about 13.3, 0.9, 1.2, 3.3, and 1.0 residues of mannose, xylose, glucose, GlcNAc, and GalNAc, respectively. RNase DdI has two characteristic conserved segments of the RNase T2 family, and thus belongs to the RNase T2 family. Considering the fact that most of the RNase activity of D. discoideum is present in the lysosomal fraction [Wiener and Ashworth (1970) Biochem. J. 118, 505-512], it was concluded that the lysosomal RNase in D. discoideum is a member of the RNase T2 family. The amino acid sequence of RNase DdI is highly homologous with that of Physarum polycephalum RNase (RNase Phyb), and its amino acid sequence seems to be similar to those of plant/animal type RNases, rather than fungal RNases. The location of RNase DdI in the phylogenetic tree of the RNase T2 family was estimated.
通过SDS-聚丙烯酰胺凝胶电泳从细胞黏菌（盘基网柄菌）细胞中分离出一种碱基非特异性酸性核糖核酸酶，其处于均一状态（约2.4 kDa）。该核糖核酸酶（核糖核酸酶DdI）的最适pH为5.0。通过蛋白质化学、数据库搜索（盘基网柄菌数据库Dicty cDB）以及对同一文库中cDNA的进一步序列分析相结合的方法确定了核糖核酸酶DdI的氨基酸序列。核糖核酸酶DdI由198个氨基酸残基组成，分别含有约13.3、0.9、1.2、3.3和1.0个甘露糖、木糖、葡萄糖、N-乙酰葡糖胺和N-乙酰半乳糖胺残基。核糖核酸酶DdI具有核糖核酸酶T2家族的两个特征性保守区段，因此属于核糖核酸酶T2家族。鉴于盘基网柄菌的大多数核糖核酸酶活性存在于溶酶体部分[维纳和阿什沃思（1970年），《生物化学杂志》118卷，505 - 512页]，得出结论：盘基网柄菌中的溶酶体核糖核酸酶是核糖核酸酶T2家族的成员。核糖核酸酶DdI的氨基酸序列与多头绒泡菌核糖核酸酶（核糖核酸酶Phyb）高度同源，并且其氨基酸序列似乎与植物/动物型核糖核酸酶相似，而不是与真菌核糖核酸酶相似。估计了核糖核酸酶DdI在核糖核酸酶T2家族系统发育树中的位置。
