7o3i
Cystal structure of Zymogen Granule Protein 16 (ZG16)
Structural highlights
FunctionZG16_HUMAN May play a role in protein trafficking. May act as a linker molecule between the submembranous matrix on the luminal side of zymogen granule membrane (ZGM) and aggregated secretory proteins during granule formation in the TGN.[1] Publication Abstract from PubMedZymogen granule membrane protein 16 (ZG16) is produced in organs that secrete large quantities of enzymes and other proteins into the digestive tract. ZG16 binds microbial pathogens, and lower ZG16 expression levels correlate with colorectal cancer, but the physiological function of the protein is poorly understood. One prominent attribute of ZG16 is its ability to bind glycans, but other aspects of the protein may also contribute to activity. An intriguing feature of ZG16 is a CXXC motif at the carboxy terminus. Here, we describe crystal structures and biochemical studies showing that the CXXC motif is on a flexible tail, where it contributes little to structure or stability but is available to engage in redox reactions. Specifically, we demonstrate that the ZG16 cysteine thiols can be oxidized to a disulfide by quiescin sulfhydryl oxidase 1, which is a sulfhydryl oxidase present together with ZG16 in the Golgi apparatus and in mucus, as well as by protein disulfide isomerase. ZG16 crystal structures also draw attention to a nonproline cis peptide bond that can isomerize within the protein and to the mobility of glycine-rich loops in the glycan-binding site. An understanding of the properties of the ZG16 CXXC motif and the discovery of internal conformational switches extend existing knowledge relating to the glycan-binding activity of the protein. Conformational switches and redox properties of the colon cancer-associated human lectin ZG16.,Javitt G, Kinzel A, Reznik N, Fass D FEBS J. 2021 Jun 2. doi: 10.1111/febs.16044. PMID:34077620[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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