title: "Subcellular proteomics" of neuromelanin granules isolated from the human brain.
abstract: "Subcellular proteomics" is currently the most effective approach to characterize subcellular compartments. Based on the powerful combination of subcellular fractionation and protein identification by LC-MS/MS we were able for the first time to 1) isolate intact neuromelanin granules from the human brain and 2) establish the first protein profile of these granules. This compartment containing neuromelanin (NM) is primarily located in the primate's substantia nigra, one of the main brain regions that severely degenerates in Parkinson disease. We used mechanic tissue disaggregation, discontinuous sucrose gradient centrifugation, cell disruption, and organelle separation to isolate NM granules from human substantia nigra. Using transmission electron microscopy we demonstrated that the morphological characteristics of the isolated NM granules are similar to those described in human brain tissue. Fundamentally we found numerous proteins definitely demonstrating a close relationship of NM-containing granules with lysosomes or lysosome-related organelles originating from the endosome-lysosome lineage. Intriguingly we further revealed the presence of endoplasmic reticulum-derived chaperones, especially the transmembrane protein calnexin, which recently has been located in lysosome-related melanosomes and has been suggested to be a melanogenic chaperone.
authors.affiliation: Department of Clinical Neurochemistry, Clinic and Polyclinic for Psychiatry and Psychotherapy, and "The National Parkinson Foundation Research Laboratories," Miami, Florida, USA. florian.tribl@mail.uni-wuerzburg.de
authors.forename: Florian
authors.initials: F
authors.lastname: Tribl
authors.forename: Manfred
authors.initials: M
authors.lastname: Gerlach
authors.forename: Katrin
authors.initials: K
authors.lastname: Marcus
authors.forename: Esther
authors.initials: E
authors.lastname: Asan
authors.forename: Thomas
authors.initials: T
authors.lastname: Tatschner
authors.forename: Thomas
authors.initials: T
authors.lastname: Arzberger
authors.forename: Helmut E
authors.initials: HE
authors.lastname: Meyer
authors.forename: Gerhard
authors.initials: G
authors.lastname: Bringmann
authors.forename: Peter
authors.initials: P
authors.lastname: Riederer
mesh_terms: D037281:Calnexin / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D002851:Chromatography, High Pressure Liquid; D003594:Cytoplasmic Granules / Q000378:metabolism* / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D008543:Melanins / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D010455:Peptides / Q000032:analysis; D040901:Proteomics; D021241:Spectrometry, Mass, Electrospray Ionization; D013347:Subcellular Fractions / Q000378:metabolism; D013378:Substantia Nigra / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D008543:Melanins; D010455:Peptides; C014121:neuromelanin; D037281:Calnexin