Pancreatic Zymogen Granule Membrane Proteins: Molecular Details Begin to Emerge

Digestion ◽  
1994 ◽  
Vol 55 (4) ◽  
pp. 191-199 ◽  
Author(s):  
Andreas C.C. Wagner ◽  
John A. Williams
Keyword(s):  
Membrane Proteins ◽  
Zymogen Granule ◽  
Granule Membrane ◽  
Granule Membrane Proteins

TOPOLOGY ANALYSIS OF PANCREATIC ZYMOGEN GRANULE MEMBRANE PROTEINS

Pancreas ◽  
2007 ◽  
pp. 396 ◽  
Author(s):  
X. Chen ◽  
E. S. Simon ◽  
P. C. Andrews ◽  
J. A. Williams
Keyword(s):  
Membrane Proteins ◽  
Zymogen Granule ◽  
Topology Analysis ◽  
Granule Membrane ◽  
Granule Membrane Proteins

scholarly journals Global Topology Analysis of Pancreatic Zymogen Granule Membrane Proteins

2008 ◽  
Vol 7 (12) ◽  
pp. 2323-2336 ◽  
Author(s):  
Xuequn Chen ◽  
Peter J. Ulintz ◽  
Eric S. Simon ◽  
John A. Williams ◽  
Philip C. Andrews
Keyword(s):  
Membrane Proteins ◽  
Zymogen Granule ◽  
Topology Analysis ◽  
Global Topology ◽  
Granule Membrane ◽  
Granule Membrane Proteins

scholarly journals Specific and azurophilic granules from rabbit polymorphonuclear leukocytes. I. Isolation and characterization of membrane and content subfractions.

1983 ◽  
Vol 96 (4) ◽  
pp. 1030-1039 ◽  
Author(s):  
W J Brown ◽  
W A Shannon ◽  
W J Snell
Keyword(s):  
Membrane Proteins ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Protein Composition ◽  
Granule Protein ◽  
Isolation And Characterization ◽  
Cytoplasmic Face ◽  
Sds Page ◽  
Granule Membrane ◽  
Granule Membrane Proteins

The specific and azurophilic granules of rabbit polymorphonuclear heterophils (PMNs) have been isolated and fractionated into membrane and extractable subfractions. Analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) revealed several features of the protein composition of the two granules: (a) Whereas each type of granule had 40-60 proteins separable on one-dimensional gradient gels, few of the proteins were common to both granules. (b) The proteins of the extractable fractions (which comprised approximately 98% of the total granule protein) of each granule were distinct from the proteins of the membrane fractions (which comprised approximately 2% of the total granule protein). (c) The extractable proteins co-migrated with those collected from the medium of ionophore-treated, degranulating PMNs and therefore were defined as content proteins. These results were confirmed by radiolabeling studies. Lactoperoxidase-catalyzed iodination of intact granules did not label the content proteins but did label proteins that co-migrated with major granule membrane proteins. Moreover, disruption of the granules before iodination led to labeling of both content and membrane proteins. We conclude that the membranes of specific and azurophilic granules, which arise from different faces of the Golgi complex, are composed of unique sets of membrane proteins some of which are exposed on the cytoplasmic face of the granules.

scholarly journals Mistargeting of secretory cargo in retromer-deficient cells

2020 ◽  
pp. dmm.046417
Author(s):  
Sarah D. Neuman ◽  
Erica L. Terry ◽  
Jane E. Selegue ◽  
Amy T. Cavanagh ◽  
Arash Bashirullah
Keyword(s):  
Membrane Proteins ◽  
Salivary Glands ◽  
Secretory Granule ◽  
Complex Function ◽  
Amyloid Β ◽  
Secretory Cells ◽  
Regulated Exocytosis ◽  
Retromer Complex ◽  
Granule Membrane ◽  
Granule Membrane Proteins

Intracellular trafficking is a basic and essential cellular function required for delivery of proteins to the appropriate subcellular destination; this process is especially demanding in professional secretory cells, which synthesize and secrete massive quantities of cargo proteins via regulated exocytosis. The Drosophila larval salivary glands are professional secretory cells that synthesize and secrete mucin proteins at the onset of metamorphosis. Using the larval salivary glands as a model system, we have identified a role for the highly conserved retromer complex in trafficking of secretory granule membrane proteins. We demonstrate that retromer-dependent trafficking via endosomal tubules is induced at the onset of secretory granule biogenesis, and that recycling via endosomal tubules is required for delivery of essential secretory granule membrane proteins to nascent granules. Without retromer function, nascent granules do not contain the proper membrane proteins; as a result, cargo from these defective granules is mistargeted to Rab7-positive endosomes, where it progressively accumulates to generate dramatically enlarged endosomes. Retromer complex dysfunction is strongly associated with neurodegenerative diseases, including Alzheimer's disease, characterized by accumulation of amyloid β (Aβ). We show that ectopically expressed amyloid precursor protein (APP) undergoes regulated exocytosis in salivary glands and accumulates within enlarged endosomes in retromer-deficient cells. These results highlight recycling of secretory granule membrane proteins as a critical step during secretory granule maturation and provide new insights into our understanding of retromer complex function in secretory cells. These findings also suggest that missorting of secretory cargo, including APP, may contribute to the progressive nature of neurodegenerative disease.

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