title: Quantitative proteomics analysis of pancreatic zymogen granule membrane proteins.
abstract: Pancreatic zymogen granules (ZG) are specialized for digestive enzyme storage and regulated secretion in the exocrine pancreas and are a classical model for studying secretory granule function. To understand the function of this organelle, we have conducted a proteomic study to identify the ZG membrane proteins from ZGs purified by Percoll gradient centrifugation. By combining multiple separation strategies including two-dimensional gel electrophoresis and two-dimensional liquid chromatography with tandem mass spectrometry (TMS), we identified 101 proteins from purified ZG membranes including a large number of proteins previously unknown on ZG membranes. To distinguish intrinsic membrane proteins from soluble and peripheral membrane proteins, a quantitative proteomics strategy was developed to measure the enrichment of intrinsic membrane proteins through the purification steps by labeling crude, KBr-, and Na(2)CO(3)-washed ZG membranes with multiplexed isobaric tags (iTRAQ), 114, 116 and 117, respectively. The proteins with 117:114 ratios greater than one correlated well with known or predicted intrinsic membrane proteins.
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Xuequn
authors.initials: X
authors.lastname: Chen
authors.forename: Philip C
authors.initials: PC
authors.lastname: Andrews
mesh_terms: D000818:Animals; D002458:Cell Fractionation; D002499:Centrifugation, Density Gradient; D002853:Chromatography, Liquid; D030562:Databases, Protein; D015180:Electrophoresis, Gel, Two-Dimensional; D008565:Membrane Proteins / Q000032:analysis*; D010179:Pancreas / Q000737:chemistry*; D040901:Proteomics / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D022142:Secretory Vesicles / Q000737:chemistry*; D013194:Staining and Labeling; D053719:Tandem Mass Spectrometry
chemical_list: D008565:Membrane Proteins