BIOSYNTHESIS AND MOLECULAR-CLONING OF SULFATED GLYCOPROTEIN-1 SECRETED BY RAT SERTOLI CELLS - SEQUENCE SIMILARITY WITH THE 70-KILODALTON PRECURSOR TO SULFATIDE/GM1 ACTIVATOR
BIOSYNTHESIS AND MOLECULAR-CLONING OF SULFATED GLYCOPROTEIN-1 SECRETED BY RAT SERTOLI CELLS - SEQUENCE SIMILARITY WITH THE 70-KILODALTON PRECURSOR TO SULFATIDE/GM1 ACTIVATOR
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DOI：
10.1021/bi00412a050
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发表时间：
1988-06-14
期刊：
影响因子：
2.9
通讯作者：
GRISWOLD, MD
中科院分区：
文献类型：
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作者：
COLLARD, MW;SYLVESTER, SR;GRISWOLD, MD
硫酸化糖蛋白1（Sulfated glycoprotein 1，SGP-1）是大鼠睾丸支持细胞分泌的丰富蛋白质之一。脉冲追踪标记表明，SGP-1合成为共翻译糖基化的67千道尔顿（kDa）前体，在分泌到细胞外间隙之前，该前体在翻译后修饰为70千道尔顿形式。从免疫纯化的mRNA构建质粒cDNA文库，并分离编码整个蛋白质编码序列的两个重叠克隆。cDNA代表5“非编码序列的27个核苷酸、编码序列的1554个核苷酸和3”非编码序列的594个核苷酸。衍生的SGP-1序列含有554个氨基酸，分子量为61，123。序列中存在四个潜在的N-糖基化位点。SGP-1的内部区域显示与人硫苷脂/GM 1激活剂（SAP-1）描述的67个N-末端氨基酸78%的序列同一性。序列比较表明，SGP-1是前体硫苷脂/Gm 1激活剂，然而，从支持细胞分泌的蛋白质是不同的蛋白水解加工和溶酶体区室化已被描述为人类成纤维细胞。内部序列相似性的存在表明，三个额外的结合位点可能发生在SGP-1。北方印迹显示在所有检查的组织中2.6-脱氢酶SGP-1 mRNA的表达水平相似。用免疫荧光和原位杂交技术将SGP-1在睾丸中的合成定位于Sertoli细胞。
Sulfated glycoprotein 1 (SGP-1) is one of the abundant proteins secreted by rat Sertoli cells. Pulse-chase labeling shows that SGP-1 is synthesized as a cotranslationally glycosylated 67-kilodalton (kDa) precursor which is posttranslationally modified to a 70-kDa form before secretion to the extracellular space. A plasmid cDNA library was constructed from immunopurified mRNA, and two overlapping clones coding for the entire protein coding sequence were isolated. The cDNAs represent 27 nucleotides of 5'' noncoding sequence, 1554 nucleotides of coding sequence, and 594 nucleotides of 3'' noncoding sequence. The derived SGP-1 sequence contains 554 amino acids and has a molecular weight of 61,123. Four potential N-glycosylation sites occur within the sequence. An internal region of SGP-1 shows 78% sequence identity with the 67 N-terminal amino acids described for human sulfatide/GM1 activator (SAP-1). Sequence comparisons suggest that SGP-1 is the precursor to sulfatide/Gm1 activator; however, the secretion of the protein from Sertoli cells is distinct from the proteolytic processing and lysosomal compartmentalization which have been described for human fibroblasts. The presence of internal sequence similarity suggests that three additional binding sites may occur in SGP-1. Northern blots show similar levels of expression for the 2.6-kilobase SGP-1 mRNA in all tissues examined. The site of SGP-1 synthesis in testis was localized to Sertoli cells by immunofluorescence and in situ hybridization.