title: MALDI/post ionization-ion mobility mass spectrometry of noncovalent complexes of dopamine receptors' epitopes.
abstract: Protein domains involved in receptor heteromer formation are disordered and rich in the amino acids necessary for the formation of noncovalent complexes (NCX). We present mass spectral NCX data from proteins and protein receptors' epitopes obtained by combining ion mobility (IM) and MALDI. We focus on NCX involved in heteromer formation occurring between epitopes of the Dopamine D2 (D2R) and Adenosine A2A receptors (A2AR) as well as D2R and the α2 nicotinic (NR) receptor's subunit. The IM data yield information on the gas phase conformation of the singly charged NCX which are observed either directly from MALDI or as codesorbed neutrals that are subsequently postionized by a time-delayed excimer laser pulse directed onto a portion of the neutral plume created by the MALDI desorption laser. Imaging mass spectrometry of the matrix/epitope dried droplet surface shows that the acidic and basic epitopes and their NCX are found to be spatially collocated within regions as small as 25 × 50 μm(2). Subtle differences in the relative abundance of protonated and cationized NCX and epitopes are measured in spatial regions near the sodium-rich outer border of the droplet.
authors.affiliation: NIDA IRP, NIH Structural Biology Unit Cellular Neurobiology Branch , 333 Cassell Drive, Baltimore, Maryland 21224, United States.
authors.forename: Amina S
authors.initials: AS
authors.lastname: Woods
authors.forename: Shelley N
authors.initials: SN
authors.lastname: Jackson
authors.forename: Ernest K
authors.initials: EK
authors.lastname: Lewis
authors.forename: Thomas
authors.initials: T
authors.lastname: Egan
authors.forename: Ludovic
authors.initials: L
authors.lastname: Muller
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Tabet
authors.forename: J Albert
authors.initials: JA
authors.lastname: Schultz
mesh_terms: D002147:Calmodulin / Q000737:chemistry; D000939:Epitopes / Q000032:analysis / Q000737:chemistry*; D007091:Image Processing, Computer-Assisted; D013058:Mass Spectrometry / Q000379:methods; D010455:Peptides / Q000032:analysis / Q000737:chemistry; D043705:Receptor, Adenosine A2A / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D011954:Receptors, Dopamine / Q000737:chemistry* / Q000276:immunology*; D017448:Receptors, Dopamine D2 / Q000737:chemistry / Q000276:immunology / Q000502:physiology; D011978:Receptors, Nicotinic / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods
chemical_list: D002147:Calmodulin; D000939:Epitopes; D010455:Peptides; D043705:Receptor, Adenosine A2A; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D011978:Receptors, Nicotinic