In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 105, No. 20 ( 2008-05-20), p. 7129-7134
Abstract:
Despite the proclamation of Lowenstam and Weiner that crustaceans are the “champions of mineral mobilization and deposition of the animal kingdom,” relatively few proteins from the two main calcification sites in these animals, i.e., the exoskeleton and the transient calcium storage organs, have been identified, sequenced, and their roles elucidated. Here, a 65-kDa protein (GAP 65) from the gastrolith of the crayfish, Cherax quadricarinatus , is fully characterized and its function in the mineralization of amorphous calcium carbonate (ACC) of the extracellular matrix is demonstrated. GAP 65 is a negatively charged glycoprotein that possesses three predicted domains: a chitin-binding domain 2, a low-density lipoprotein receptor class A domain, and a polysaccharide deacetylase domain. Expression of GAP 65 was localized to columnar epithelial cells of the gastrolith disk during premolt. In vivo administration of GAP 65 dsRNA resulted in a significant reduction of GAP 65 transcript levels in the gastrolith disk. Such gene silencing also caused dramatic structural and morphological deformities in the chitinous-ACC extracellular matrix structure. ACC deposited in these gastroliths appeared to be sparsely packed with large elongated cavities compared with the normal gastrolith, where ACC is densely compacted. ACC spherules deposited in these gastroliths are significantly larger than normal. GAP 65, moreover, inhibited calcium carbonate crystallization in vitro and stabilized synthetic ACC. Thus, GAP 65 is the first protein shown to have dual function, involved both in extracellular matrix formation and in mineral deposition during biomineralization.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.0800193105
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2008
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
Permalink
