Carey D J, Conner K, Asundi V K, O'Mahony D J, Stahl R C, Showalter L, Cizmeci-Smith G, Hartman J, Rothblum L I
Sigfried and Janet Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania 19822, USA.
J Biol Chem. 1997 Jan 31;272(5):2873-9. doi: 10.1074/jbc.272.5.2873.
The amino acid sequence of rat N-syndecan core protein was deduced from the cloned cDNA sequence. The sequence predicts a core protein of 442 amino acids with six structural domains: an NH2-terminal signal peptide, a membrane distal glycosaminoglycan attachment domain, a mucin homology domain, a membrane proximal glycosaminoglycan attachment domain, a single transmembrane domain, and a noncatalytic COOH-terminal cytoplasmic domain. Transfection of human 293 cells resulted in the expression of N-syndecan that was modified by heparan sulfate chain addition. Heparitinase digestion of the expressed proteoglycan produced a core protein that migrated on SDS-polyacrylamide gels at an apparent molecular weight of 120, 000, identical to N-syndecan synthesized by neonatal rat brain or Schwann cells. Rat genomic DNA coding for N-syndecan was isolated by hybridization screening. The rat N-syndecan gene is comprised of five exons. Each exon corresponds to a specific core protein structural domain, with the exception of the fifth exon, which contains the coding information for both the transmembrane and cytoplasmic domains as well as the 3'-untranslated region of the mRNA. The first intron is large, with a length of 22 kilobases. The expression of N-syndecan was investigated in late embryonic, neonatal, and adult rats by immunoblotting and Northern blotting analysis. Among the tissues and developmental stages studied, high levels of N-syndecan expression were restricted to the early postnatal nervous system. N-syndecan was expressed in all regions of the nervous system, including cortex, midbrain, spinal cord, and peripheral nerve. Immunohistochemical staining revealed high levels of N-syndecan expression in all brain regions and fiber tract areas.
大鼠N-多配体蛋白聚糖核心蛋白的氨基酸序列是从克隆的cDNA序列推导出来的。该序列预测有一个由442个氨基酸组成的核心蛋白，具有六个结构域：一个NH2末端信号肽、一个膜远端糖胺聚糖附着结构域、一个粘蛋白同源结构域、一个膜近端糖胺聚糖附着结构域、一个单一跨膜结构域和一个非催化性COOH末端胞质结构域。人293细胞的转染导致了N-多配体蛋白聚糖的表达，该蛋白聚糖通过添加硫酸乙酰肝素链进行修饰。对表达的蛋白聚糖进行肝素酶消化产生了一种核心蛋白，该核心蛋白在SDS-聚丙烯酰胺凝胶上以120,000的表观分子量迁移，与新生大鼠脑或雪旺细胞合成的N-多配体蛋白聚糖相同。通过杂交筛选分离出编码N-多配体蛋白聚糖的大鼠基因组DNA。大鼠N-多配体蛋白聚糖基因由五个外显子组成。每个外显子对应一个特定的核心蛋白结构域，但第五个外显子除外，它包含跨膜和胞质结构域以及mRNA的3'-非翻译区的编码信息。第一个内含子很大，长度为22千碱基。通过免疫印迹和Northern印迹分析研究了N-多配体蛋白聚糖在胚胎后期、新生和成年大鼠中的表达。在所研究的组织和发育阶段中，N-多配体蛋白聚糖的高表达仅限于出生后早期的神经系统。N-多配体蛋白聚糖在神经系统的所有区域表达，包括皮质、中脑、脊髓和周围神经。免疫组织化学染色显示在所有脑区和纤维束区域N-多配体蛋白聚糖表达水平很高。
