Expression of collagen XVIII and localization of its glycosaminoglycan attachment sites
Expression of collagen XVIII and localization of its glycosaminoglycan attachment sites
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DOI：
10.1074/jbc.m209276200
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发表时间：
2003-01-17
影响因子：
4.8
通讯作者：
Halfter, W
中科院分区：
文献类型：
--
作者：
Dong, SC;Cole, GJ;Halfter, W
XVIII胶原蛋白是目前已知的唯一一种携带硫酸乙酰肝素糖胺聚糖侧链的胶原蛋白。通过鸡胶原XVIII全长真核表达和定点突变，确定核心蛋白中糖胺多聚糖结合位点的数目和位置。在核心蛋白的中部和N端检测到3个携带糖胺聚糖侧链的Ser-Gly共有序列。Ser-Gly共有序列中的一个带有硫酸肝素侧链，其余两个含有硫酸软骨素和硫酸肝素的混合侧链；因此，重组胶原XVIII是硫酸肝素和软骨素蛋白多糖的杂交体。相比之下，到目前为止，所有被检测的鸡组织中的XVIII胶原蛋白都只有硫酸乙酰肝素侧链，这表明在体外表达的蛋白质的翻译后修饰与在活胚胎中发生的过程并不完全相同。将各种突变的XVIII型胶原蛋白与视网膜基底膜孵育表明，硫酸乙酰肝素糖胺聚糖侧链介导了XVIII型胶原蛋白与基底膜的结合。
Collagen XVIII is the only currently known collagen that carries heparan sulfate glycosaminoglycan side chains. The number and location of the glycosaminoglycan attachment sites in the core protein were determined by eukaryotic expression of full-length chick collagen XVIII and site-directed mutagenesis. Three Ser-Gly consensus sequences carrying glycosaminoglycan side chains were detected in the middle and N-terminal part of the core protein. One of the Ser-Gly consensus sequences carried a heparan sulfate side chain, and the remaining two had mixed chondroitin and heparan sulfate side chains; thus, recombinant collagen XVIII was a hybrid of heparan sulfate and chondroitin proteoglycan. In contrast, collagen XVIII from all chick tissues so far assayed have exclusively heparan sulfate side chains, indicating that the posttranslational modification of proteins expressed in vitro is not entirely identical to the processing that occurs in a living embryo. Incubating the various mutated collagen XVIIIs with retinal basement membranes showed that the heparan sulfate glycosaminoglycan side chains mediate the binding of collagen XVIII to basement membranes.