Fisher L W, Heegaard A M, Vetter U, Vogel W, Just W, Termine J D, Young M F
Bone Research Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
J Biol Chem. 1991 Aug 5;266(22):14371-7.
Biglycan (PG-I, DS-PG-1, PG-S1) is a small cellular or pericellular matrix proteoglycan that is closely related in structure to two other small proteoglycans, decorin (PG-II, PG-S2, DS-PG2, or PG-40) and fibromodulin. The core protein is made up predominantly of a series of 11 tandem repeats that appear to have been used throughout evolution for protein-protein, protein-cell, or cell-cell interactions. The function of biglycan is unclear at this time, but it has been shown to bind transforming growth factor beta in vitro. We have cloned and partially sequenced the approximately 8-kilobase pair human biglycan gene. The gene consists of eight exons including one in the sequence that encodes the 5'-untranslated region of the mRNA. The first and seventh introns are approximately 1 kilobase pair, while the remainder are shorter. With the exception of the first two introns, all of the introns are spread throughout the hydrophobic repeat domain. The 500-base pair 5' to the start of transcription contains several elements that strongly suggest that it contains a significant amount of the gene promoter. The elements include one AP2 and five SP1 consensus sequences. Like in many other genes, the biglycan gene promoter lacks both a CAAT and TATA box but is rich in GC content. Using 3H-labeled cDNA and in situ hybridization and autoradiography of human chromosomes, the human gene was localized to the end of the long arm of the X chromosome (Xq27-ter). The relationship of biglycan to a number of other proteins containing the leucine-rich repeats is discussed with respect to homologies of cysteine regions immediately adjacent to the repeat sequences.
双糖链蛋白聚糖（PG-I、DS-PG-1、PG-S1）是一种小分子细胞内或细胞周围基质蛋白聚糖，其结构与另外两种小分子蛋白聚糖，即核心蛋白聚糖（PG-II、PG-S2、DS-PG2或PG-40）和纤调蛋白密切相关。核心蛋白主要由一系列11个串联重复序列组成，这些重复序列在整个进化过程中似乎都被用于蛋白质-蛋白质、蛋白质-细胞或细胞-细胞相互作用。目前双糖链蛋白聚糖的功能尚不清楚，但已表明它在体外能结合转化生长因子β。我们已经克隆了约8千碱基对的人双糖链蛋白聚糖基因并进行了部分测序。该基因由八个外显子组成，包括一个位于编码mRNA 5'-非翻译区序列中的外显子。第一个和第七个内含子约为1千碱基对，其余的较短。除前两个内含子外，所有内含子都分布在疏水重复结构域中。转录起始点上游500碱基对包含几个元件，强烈提示其含有大量基因启动子。这些元件包括一个AP2和五个SP1共有序列。与许多其他基因一样，双糖链蛋白聚糖基因启动子既没有CAAT盒也没有TATA盒，但富含GC含量。利用3H标记的cDNA以及人染色体的原位杂交和放射自显影技术，将人基因定位到X染色体长臂末端（Xq27-ter）。关于紧邻重复序列的半胱氨酸区域的同源性，讨论了双糖链蛋白聚糖与其他一些富含亮氨酸重复序列的蛋白质的关系。
