BIOSYNTHESIS AND OLIGOSACCHARIDE PROCESSING OF HUMAN TAMM-HORSFALL GLYCOPROTEIN PERMANENTLY EXPRESSED IN HELA-CELLS
BIOSYNTHESIS AND OLIGOSACCHARIDE PROCESSING OF HUMAN TAMM-HORSFALL GLYCOPROTEIN PERMANENTLY EXPRESSED IN HELA-CELLS
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DOI：
10.1006/bbrc.1993.1890
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发表时间：
1993-07-30
影响因子：
3.1
通讯作者：
RINDLER, MJ
中科院分区：
文献类型：
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作者：
SERAFINICESSI, F;MALAGOLINI, N;RINDLER, MJ
人Tamm-Horsfall糖蛋白（T-H）是由Henle袢升支肾细胞产生的糖蛋白，主要经尿排泄，其中N-糖链占T-H总重量的30%。我们研究了在HeLa细胞中永久表达的重组T-H的生物合成。从前体（84 kDa）到成熟形式（97 kDa）的转化主要取决于聚糖从高甘露糖型到多触角型的加工。从前体到成熟形式的转化非常缓慢，前体的聚糖结构似乎是尚未被高尔基体α 1，2甘露糖苷酶加工的糖蛋白的聚糖结构。由于T-H具有非常高数量的二硫键（超过50个半胱氨酸残基/mol），因此可以推断前体输出ER的限速步骤是形成正确的二硫键组。从HeLa细胞中分离的成熟T-H保留一个N-连接链，具有类似于尿T-H的高甘露糖结构。这一结果表明，在成熟的T-H中出现一个未加工的高甘露糖链是不依赖于宿主细胞的，并且很可能与T-H的一级结构有关。
Human Tamm-Horsfall glycoprotein (T-H) is produced by renal cells of ascending limb of loop of Henle and is largely excreted in urine.N-linked glycans account for close to 30% of the weight of T-H. We studied the biosynthesis of recombinant T-H permanently expressed in HeLa cells. The conversion from the precursor (84 kDa) to the mature form (97 kDa) mainly depends on the processing of glycans from the high-mannose to polyantennary type. The conversion from precursor to mature form is very slow and the glycan structure of precursor appears to be that of a glycoprotein not yet processed by Golgi α1,2 mannosidase. Since T-H has a very high number of disulfide bridges (more than 50 cysteine residues/mol) one may infer that the rate limiting step for the precursor export out of ER is the formation of a correct set of disulfide bonds. Mature T-H isolated from HeLa cells retained oneN-linked chain with the highmannose structure similarly to urinary T-H. This result indicates that the occurrence of one unprocessed high-mannose chain in mature T-H is host-cell independent and very likely related to the T-H primary structure.