title: Serum monomeric α2-macroglobulin as a clinical biomarker in diabetes.
abstract: OBJECTIVE
  Despite the number of potential biomarker proteins for diabetes, very few of them have proven useful as clinically beneficial indicators, because of the technical difficulties associated with their identification among highly abundant serum proteins. We attempted to identify a protein with distinguishable expression in human diabetes.
  
  
  METHODS
  We applied a highly efficient strategy for the purification of endogenous low abundance proteins from diabetic and non-diabetic serum samples. Extracted sera were fractionated by SDS-PAGE and protein bands were isolated and analyzed by mass spectrometry using an ion-trap mass spectrometer. The identities of the proteins were confirmed by western blotting and the serum levels evaluated.
  
  
  RESULTS
  A significantly upregulated protein in diabetic patients was identified as monomeric α2-macroglobulin. Its tetramer, another dominant circulating molecular form, was only marginally increased in diabetes.
  
  
  CONCLUSIONS
  Serum monomeric α2-macroglobulin is highly expressed in many diabetic subjects. It is identical to the human 'cardiac isoform of α2-macroglobulin' described in the literature, a well-known acute phase serum biomarker protein mechanistically involved in cardiac and atherosclerotic diseases.
authors.affiliation: Department of Endocrinology, Diabetes and Metabolism, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0374, Japan.
authors.forename: Tesshu
authors.initials: T
authors.lastname: Takada
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Kodera
authors.forename: Madoka
authors.initials: M
authors.lastname: Matsubara
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kawashima
authors.forename: Tadakazu
authors.initials: T
authors.lastname: Maeda
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Fujita
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Shichiri
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D015415:Biomarkers / Q000097:blood; D001798:Blood Proteins / Q000032:analysis / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000175:diagnosis*; D003928:Diabetic Nephropathies / Q000097:blood / Q000175:diagnosis; D003930:Diabetic Retinopathy / Q000097:blood / Q000175:diagnosis; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D011507:Proteinuria / Q000097:blood / Q000175:diagnosis; D040901:Proteomics; D055815:Young Adult; D000511:alpha-Macroglobulins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D001798:Blood Proteins; D000511:alpha-Macroglobulins