Argraves W S, Tran H, Burgess W H, Dickerson K
Biochemistry Laboratory, American Red Cross, Rockville, Maryland 20855.
J Cell Biol. 1990 Dec;111(6 Pt 2):3155-64. doi: 10.1083/jcb.111.6.3155.
We have studied the expression of fibulin in cultured fibroblasts and determined its primary structure by cDNA cloning. Our results show that fibulin is a secreted glycoprotein that becomes incorporated into a fibrillar extracellular matrix when expressed by cultured cells or added exogenously to cell monolayers. In addition, we find that fibulin is present in plasma at a level of 33 +/- 3 micrograms/ml. Sequencing of multiple fibulin cDNAs indicates that a process of alternative splicing results in the expression of three fibulin transcripts. The transcripts encode overlapping polypeptides differing only in carboxy-terminal segments. Common to the three predicted forms of fibulin is a unique 537-amino acid-long cysteine-rich polypeptide and a 29-residue signal peptide. The amino-terminal portion of fibulin contains a repeated element with potential disulfide loop structure resembling that of the complement component anaphylatoxins C3a, C4a, and C5a as well as proteins of the albumin gene family. The bulk of the remaining portion of the molecule is a series of nine EGF-like repeats.
我们研究了纤维连接蛋白在培养的成纤维细胞中的表达，并通过cDNA克隆确定了其一级结构。我们的结果表明，纤维连接蛋白是一种分泌型糖蛋白，当由培养细胞表达或外源添加到细胞单层时，它会整合到纤维状细胞外基质中。此外，我们发现血浆中纤维连接蛋白的水平为33±3微克/毫升。多个纤维连接蛋白cDNA的测序表明，可变剪接过程导致三种纤维连接蛋白转录本的表达。这些转录本编码仅在羧基末端片段不同的重叠多肽。三种预测形式的纤维连接蛋白共有的是一个独特的537个氨基酸长的富含半胱氨酸的多肽和一个29个残基的信号肽。纤维连接蛋白的氨基末端部分包含一个重复元件，其潜在的二硫键环结构类似于补体成分过敏毒素C3a、C4a和C5a以及白蛋白基因家族的蛋白质。分子其余部分的大部分是一系列九个表皮生长因子样重复序列。
