Monti E, Bassi M T, Bresciani R, Civini S, Croci G L, Papini N, Riboni M, Zanchetti G, Ballabio A, Preti A, Tettamanti G, Venerando B, Borsani G
Department of Biomedical Science and Biotechnology, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
Genomics. 2004 Mar;83(3):445-53. doi: 10.1016/j.ygeno.2003.08.019.
Several mammalian sialidases have been cloned so far and here we describe the identification and expression of a new member of the human sialidase gene family. The NEU4 gene, identified by searching sequence databases for entries showing homologies to the human cytosolic sialidase NEU2, maps in 2q37 and encodes a 484-residue protein. The polypeptide contains all the typical sialidase amino acid motifs and, apart from an amino acid stretch that appears unique among mammalian sialidases, shows a high degree of homology for NEU2 and the plasma membrane-associated (NEU3) sialidases. RNA dot-blot analysis showed a low but wide expression pattern, with the highest level in liver. Transient transfection in COS7 cells allowed the detection of a sialidase activity toward the artificial substrate 4MU-NeuAc in the acidic range of pH. Immunofluorescence staining and Western blot analysis demonstrated the association of NEU4 with the inner cell membranes.
到目前为止，已有几种哺乳动物的唾液酸酶被克隆，在此我们描述人类唾液酸酶基因家族一个新成员的鉴定和表达。通过在序列数据库中搜索与人类胞质唾液酸酶NEU2具有同源性的条目鉴定出的NEU4基因，定位于2q37，编码一个含484个氨基酸残基的蛋白质。该多肽包含所有典型的唾液酸酶氨基酸基序，除了在哺乳动物唾液酸酶中显得独特的一段氨基酸序列外，与NEU2和质膜相关（NEU3）唾液酸酶具有高度同源性。RNA斑点杂交分析显示其表达模式较低但广泛，在肝脏中水平最高。在COS7细胞中的瞬时转染使得能够检测到在酸性pH范围内针对人工底物4MU-NeuAc的唾液酸酶活性。免疫荧光染色和蛋白质印迹分析证明NEU4与细胞内膜相关。
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