ZG16p, an animal homolog of β-prism fold plant lectins, interacts with heparan sulfate proteoglycans in pancreatic zymogen granules
| Autor: | Naoshi Dohmae, Sachiko Hosokawa-Tamiya, Kyoko Kojima-Aikawa, Hidenao Toyoda, Yukiko Nakano, Akiko Kinoshita-Toyoda, Tomoko Mimura, Kaori Kumazawa-Inoue |
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| Rok vydání: | 2011 |
| Předmět: |
Molecular Sequence Data
BanLec Biology Biochemistry chemistry.chemical_compound Sulfation Affinity chromatography Lectins Zymogen granule membrane Animals Amino Acid Sequence Pancreas Glycosaminoglycans Binding Sites Secretory Vesicles Lectin Heparan sulfate Zymogen granule Recombinant Proteins Heparin lyase Rats chemistry biology.protein Proteoglycans Heparitin Sulfate Plant Lectins Heparan Sulfate Proteoglycans |
| Zdroj: | Glycobiology. 22:258-266 |
| ISSN: | 1460-2423 0959-6658 |
| DOI: | 10.1093/glycob/cwr145 |
| Popis: | ZG16p is a soluble 16 kDa pancreatic protein having structural similarities with plant β-prism fold lectins such as the banana lectin BanLec and the jackfruit lectin jacalin. ZG16p is postulated to be involved in the formation of zymogen granules by interacting with proteoglycans (PGs) localized in pancreatic exocrine granule membranes, but direct evidence was lacking. We characterized the structural properties of rat pancreatic zymogen granule PGs and examined their interaction with ZG16p. Structural analysis of the glycosaminoglycans (GAGs) showed that rat pancreatic zymogen granule PGs have heparan sulfate chains with a unique property, a high degree of sulfation (ΔUA-GlcNAc:ΔUA-GlcNS:ΔUA-GlcNAc6S:ΔUA-GlcNS6S:ΔUA2S-GlcNS:ΔUA2S-GlcNS6S, 27.9:16.6:5.7:22.5:6.2:21.1). After heparin lyase II digestion, the core proteins derived from the PGs were detected at molecular weights of 66,000 and 35,000-40,000. An overlay binding assay revealed that ZG16p binds specifically to heparan sulfate PGs by recognizing their GAG chains. Affinity chromatography demonstrated that ZG16p binds most strongly to heparin among the zymogen granule proteins. Site-directed mutational analysis revealed that the basic amino acid residues located in two putative carbohydrate-binding sites (CBSs) of ZG16p, which were found in association with the crystal structure of BanLec, are responsible for the recognition of heparin. These observations suggest that ZG16p is the primary binding partner of the granule heparan sulfate PGs. ZG16p may cross-link the granule heparan sulfate chains via two CBSs and facilitate the formation of a submembranous matrix, a sorting platform for enzyme proteins on the luminal side of the zymogen granule membrane. |
| Databáze: | OpenAIRE |
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