Document Detail

Protein-Sequence Polymorphisms and Post-translational Modifications in Proteins from Human Saliva using Top-Down Fourier-transform Ion Cyclotron Resonance Mass Spectrometry.
MedLine Citation:
PMID:  19050733     Owner:  NLM     Status:  Publisher    
Single nucleotide polymorphisms (SNPs) can result in protein sequence polymorphisms (PSPs) when codon translations are altered. Both top-down and bottom-up proteomics strategies can identify PSPs, but only if databases and software are used with this in mind. A 14319 Da protein from human saliva was characterized using the top-down approach on a hybrid linear ion-trap Fourier-transform ion cyclotron resonance mass spectrometer equipped for both collisionally-activated (CAD) and electron-capture (ECD) dissociation. Sequence tags identified the protein as Cystatin SN, and defined the N-terminal signal peptide cleavage site, as well as two disulfide bonds, in agreement with previous studies. The mass of the intact protein (< 5 ppm error) deviated from that calculated from the published gene sequence by 16.031 Da, and, based on CAD and ECD fragment ion assignments, it was concluded that the isoform of the protein analyzed carried a PSP at residue 11 such that the Pro translated from the genome was in fact Leu/Ile. An independently determined SNP (rs2070856) subsequently confirmed the genetic basis of the mass spectral interpretation and defined the residue as Leu. In another example, the PRP3 protein with mass approximately 10,999 Da was found to be an isomeric/isobaric mixture of the reported sequence with PSPs D4N or D50N (rs1049112). Both CAD and ECD datasets support two phosphorylation sites at residues Ser8 and Ser22, rather than Ser17. In the context of discovery proteomics, previously undefined PSPs and PTMs will only be detected if the logic of data processing strategies considers their presence in an unbiased fashion.
Julian P Whitelegge; Vlad Zabrouskov; Frederic Halgand; Puneet Souda; Sara Bassilian; Weihong Yan; Larry Wolinsky; Joseph A Loo; David T W Wong; Kym F Faull
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Publication Detail:
Journal Detail:
Title:  International journal of mass spectrometry     Volume:  268     ISSN:  1387-3806     ISO Abbreviation:  Int J Mass Spectrom     Publication Date:  2007 Dec 
Date Detail:
Created Date:  2009-3-5     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101137096     Medline TA:  Int J Mass Spectrom     Country:  -    
Other Details:
Languages:  ENG     Pagination:  190-197     Citation Subset:  -    
The Pasarow Mass Spectrometry Laboratory, NPI - Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, 760 West wood Plaza, Los Angeles, CA 90024.
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Grant Support
U01 DE016275-04//NIDCR NIH HHS

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