title: Full-length characterization of proteins in human populations.
abstract: BACKGROUND
  Diversity in human proteins often gives rise to pluralities of structurally similar but functionally distinct proteins. Such microheterogeneity generally escapes proteomics discovery technologies, as well as conventional immunometric assays. As an intermediate between these 2 technological approaches, targeted, full-length characterization of proteins using mass spectrometry is a suitable means of defining microheterogeneity evident in human populations.
  
  
  BACKGROUND
  We describe and explore the implications of microheterogeneity using the exemplar of human vitamin D binding protein (Gc-Globulin) as observed in cohorts of 400 individuals. Our investigations yielded: (a) population frequency data comparable to genotyping; (b) population frequency data for protein variants, with and without genotype linkage; (c) reference values for the different protein variants per cohort and genotype; and (d) associations between variant, frequency, relative abundance, and diseases.
  
  
  CONCLUSIONS
  With the exception of the genotype frequency, such population data are unique and illustrate a need to more fully understand the exact full-length qualitative and quantitative idiosyncrasies of individual proteins in relation to health and disease as part of the standardized biomarker development and clinical proteomic investigation of human proteins.
authors.affiliation: The Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Chad R
authors.initials: CR
authors.lastname: Borges
authors.forename: Doug S
authors.initials: DS
authors.lastname: Rehder
authors.forename: Jason W
authors.initials: JW
authors.lastname: Jarvis
authors.forename: Mathew R
authors.initials: MR
authors.lastname: Schaab
authors.forename: Paul E
authors.initials: PE
authors.lastname: Oran
authors.forename: Randall W
authors.initials: RW
authors.lastname: Nelson
mesh_terms: D002318:Cardiovascular Diseases / Q000378:metabolism; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism; D005838:Genotype; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D020033:Protein Isoforms; D012016:Reference Values; D014809:Vitamin D-Binding Protein / Q000737:chemistry* / Q000378:metabolism
chemical_list: D020033:Protein Isoforms; D014809:Vitamin D-Binding Protein