Delineation of Concentration Ranges and Longitudinal Changes of Human Plasma Protein Variants

Abstract

Human protein diversity arises as a result of alternative splicing, single nucleotide polymorphisms (SNPs) and posttranslational modifications. Because of these processes, each protein can exists as multiple variants in vivo. Tailored strategies are needed to study these protein variants and understand their role in health and disease. In this work we utilized quantitative mass spectrometric immunoassays to determine the protein variants concentration of beta-2-microglobulin, cystatin C, retinol binding protein, and transthyretin, in a population of 500 healthy individuals. Additionally, we determined the longitudinal concentration changes for the protein variants from four individuals over a 6 month period. Along with the native forms of the four proteins, 13 posttranslationally modified variants and 7 SNP-derived variants were detected and their concentration determined. Correlations of the variants concentration with geographical origin, gender, and age of the individuals were also examined. This work represents an important step toward building a catalog of protein variants concentrations and examining their longitudinal changes.

Development of quantitative mass spectrometric immunoassay for serum amyloid A

“…MSIA has been used for both qualitative and quantitative analyses of multiple protein entities (Kiernan et al, 2006, Trenchevska et al, 2014). In previous work, we reported several truncated SAA proteoforms originating from SAA 1.1 and SAA 2.1, lacking one or more amino acids from the N - and/or C -terminus by qualitative MSIA (Kiernan et al, 2003).…”

Mass Spectrometric Immunoassays in Characterization of Clinically Significant Proteoforms

“…The range of proteoforms concentrations in large cohorts (more than 500 samples) was analyzed in healthy population [112], in an endeavor termed population proteomics [117,118]. Population proteomics studies have provided information about the distribution and frequency of abundance of proteoforms originating from proteins such as cystatin C, transthyretin, beta 2-microglobulin and retinol binding protein [114,115].…”

“…Population proteomics studies have provided information about the distribution and frequency of abundance of proteoforms originating from proteins such as cystatin C, transthyretin, beta 2-microglobulin and retinol binding protein [114,115]. In addition, changes in protein profiles in time have been monitored, by performing a longitudinal study of the proteoform distribution [112]. …”

Mass Spectrometric Immunoassays for Discovery, Screening and Quantification of Clinically Relevant Proteoforms

“…When the RBP mass spectrometric immunoassay was applied to two large cohorts of healthy subjects, additional truncated proteoforms were detected, including des-NLL, des-RNLL and des-SERNLL RBP proteoforms [50,51]. A fully quantitative RBP mass spectrometric immunoassay was subsequently developed [18] and first applied to determine the concentration of all RBP proteoforms in a population of 500 healthy individuals [52]. Wild-type (full-length) RBP was present at the highest concentration; des-L was less abundant but still present in all 500 samples, whereas des-LL RBP was detected and quantified in half of the cohort.…”