title: An insight into iTRAQ: where do we stand now?
abstract: The iTRAQ (isobaric tags for relative and absolute quantification) technique is widely employed in proteomic workflows requiring relative quantification. Here, we review the iTRAQ literature; in particular, we focus on iTRAQ usage in relation to other commonly used quantitative techniques e.g. stable isotope labelling in culture (SILAC), label-free methods and selected reaction monitoring (SRM). As a result, we identify several issues arising with respect to iTRAQ. Perhaps frustratingly, iTRAQ's attractiveness has been undermined by a number of technical and analytical limitations: it may not be truly quantitative, as the changes in abundance reported will generally be underestimated. We discuss weaknesses and strengths of iTRAQ as a methodology for relative quantification in the light of this and other technical issues. We focus on technical developments targeted at iTRAQ accuracy and precision, use of 4-plex over 8-plex reagents and application of iTRAQ to post-translational modification (PTM) workflows. We also discuss iTRAQ in relation to label-free approaches, to which iTRAQ is losing ground.
authors.affiliation: The ChELSI Institute, Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK.
authors.forename: Caroline
authors.initials: C
authors.lastname: Evans
authors.forename: Josselin
authors.initials: J
authors.lastname: Noirel
authors.forename: Saw Yen
authors.initials: SY
authors.lastname: Ow
authors.forename: Malinda
authors.initials: M
authors.lastname: Salim
authors.forename: Ana G
authors.initials: AG
authors.lastname: Pereira-Medrano
authors.forename: Narciso
authors.initials: N
authors.lastname: Couto
authors.forename: Jagroop
authors.initials: J
authors.lastname: Pandhal
authors.forename: Duncan
authors.initials: D
authors.lastname: Smith
authors.forename: Trong Khoa
authors.initials: TK
authors.lastname: Pham
authors.forename: Esther
authors.initials: E
authors.lastname: Karunakaran
authors.forename: Xin
authors.initials: X
authors.lastname: Zou
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Biggs
authors.forename: Phillip C
authors.initials: PC
authors.lastname: Wright
mesh_terms: D000818:Animals; D006801:Humans; D007553:Isotope Labeling / Q000295:instrumentation / Q000379:methods; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods; D011506:Proteins / Q000737:chemistry*; D040901:Proteomics / Q000295:instrumentation / Q000379:methods*
chemical_list: D011506:Proteins