Funderburgh J L, Funderburgh M L, Brown S J, Vergnes J P, Hassell J R, Mann M M, Conrad G W
Division of Biology, Kansas State University, Manhattan 66506.
J Biol Chem. 1993 Jun 5;268(16):11874-80.
Amino acid sequence from tryptic peptides of three different bovine corneal keratan sulfate proteoglycan (KSPG) core proteins (designated 37A, 37B, and 25) showed similarities to the sequence of a chicken KSPG core protein lumican. Bovine lumican cDNA was isolated from a bovine corneal expression library by screening with chicken lumican cDNA. The bovine cDNA codes for a 342-amino acid protein, M(r) 38,712, containing amino acid sequences identified in the 37B KSPG core protein. The bovine lumican is 68% identical to chicken lumican, with an 83% identity excluding the N-terminal 40 amino acids. Location of 6 cysteine and 4 consensus N-glycosylation sites in the bovine sequence were identical to those in chicken lumican. Bovine lumican had about 50% identity to bovine fibromodulin and 20% identity to bovine decorin and biglycan. About two-thirds of the lumican protein consists of a series of 10 amino acid leucine-rich repeats that occur in regions of calculated high beta-hydrophobic moment, suggesting that the leucine-rich repeats contribute to beta-sheet formation in these proteins. Sequences obtained from 37A and 25 core proteins were absent in bovine lumican, thus predicting a unique primary structure and separate mRNA for each of the three bovine KSPG core proteins.
三种不同的牛角膜硫酸角质素蛋白聚糖（KSPG）核心蛋白（分别命名为37A、37B和25）的胰蛋白酶肽段氨基酸序列显示出与鸡KSPG核心蛋白核心蛋白聚糖的序列相似性。通过用鸡核心蛋白聚糖cDNA进行筛选，从牛角膜表达文库中分离出牛核心蛋白聚糖cDNA。该牛cDNA编码一个342个氨基酸的蛋白质，分子量为38712，包含在37B KSPG核心蛋白中鉴定出的氨基酸序列。牛核心蛋白聚糖与鸡核心蛋白聚糖的同源性为68%，如果不包括N端的40个氨基酸，同源性为83%。牛序列中6个半胱氨酸和4个共有N-糖基化位点的位置与鸡核心蛋白聚糖中的相同。牛核心蛋白聚糖与牛纤调蛋白的同源性约为50%，与牛饰胶蛋白和双糖链蛋白聚糖的同源性为20%。核心蛋白聚糖约三分之二的蛋白质由一系列10个氨基酸的富含亮氨酸重复序列组成，这些序列出现在计算出的高β-疏水矩区域，这表明富含亮氨酸的重复序列有助于这些蛋白质中β-折叠的形成。在牛核心蛋白聚糖中没有获得来自37A和25核心蛋白的序列，因此预测三种牛KSPG核心蛋白各自具有独特的一级结构和单独的mRNA。
