Watorek W, van Halbeek H, Travis J
Institute of Biochemistry, Wroclaw University, Poland.
Biol Chem Hoppe Seyler. 1993 Jun;374(6):385-93. doi: 10.1515/bchm3.1993.374.1-6.385.
The two proteinases found in human neutrophil granules, elastase and cathepsin G, each are normally isolated as a mixture of isoforms differing only in carbohydrate content. Elastase has two N-glycosylation sites occupied (Asn-45 and Asn-144), whereas cathepsin G has only one (Asn-64). Analysis of a minor form of elastase (E-1) and cathepsin G (C-1) indicates that the carbohydrate structures at each glycosylation site are complex-type bi-antennary chains usually associated with secretory glycoproteins. In contrast, the isoforms E-3 and C-3, the major forms of elastase and cathepsin G respectively, contain exclusively truncated, oligomannose-type chains at the same positions in the sequence of each protein. These data suggest the possibility that certain elastase and cathepsin G isoforms (E-1 and C-1) might be destined for secretory, others (E-3 and C-3) for lysosomal functions.
在人类嗜中性粒细胞颗粒中发现的两种蛋白酶，即弹性蛋白酶和组织蛋白酶G，通常各自以仅在碳水化合物含量上有所不同的同工型混合物形式被分离出来。弹性蛋白酶有两个被占据的N-糖基化位点（天冬酰胺-45和天冬酰胺-144），而组织蛋白酶G只有一个（天冬酰胺-64）。对一种次要形式的弹性蛋白酶（E-1）和组织蛋白酶G（C-1）的分析表明，每个糖基化位点的碳水化合物结构是通常与分泌性糖蛋白相关的复合型双天线链。相比之下，弹性蛋白酶和组织蛋白酶G的主要形式，即同工型E-3和C-3，在每种蛋白质序列的相同位置仅含有截短的寡甘露糖型链。这些数据表明，某些弹性蛋白酶和组织蛋白酶G同工型（E-1和C-1）可能注定用于分泌功能，而其他同工型（E-3和C-3）则用于溶酶体功能。
