title: Human CRISP-3 binds serum alpha(1)B-glycoprotein across species.
abstract: BACKGROUND
  CRISP-3 was previously shown to be bound to alpha(1)B-glycoprotein (A1BG) in human serum/plasma. All mammalian sera are supposed to contain A1BG, although its presence in rodent sera is not well-documented. Since animal sera are often used to supplement buffers in experiments, in particular such that involve cell cultures, binding proteins present in sera might interfere in the experiments.
  
  
  METHODS
  We examined sera from five different animal species for CRISP-3 binding proteins using gel filtration and ligand blotting. We developed a rapid method for isolation of proteins that bind to human CRISP-3 and identified the isolated proteins by mass spectrometry and N-terminal sequencing.
  
  
  RESULTS
  We identified A1BG as a CRISP-3 binding protein in sera from cow, horse and rabbit. CRISP-3 bound kininogen 1 in mouse serum, whereas rat serum showed no CRISP-3 binding activity. In equine serum, we furthermore detected a possible CRISP, already bound to A1BG.
  
  
  CONCLUSIONS
  It seems to be a common mechanism that A1BGs bind CRISPs, also across species. Apart from the possible physiological implications hereof, complex binding of CRISPs by A1BG (and other proteins) may interfere with the detection and function of CRISPs, when these are studied in the presence of animal sera.
authors.affiliation: Granulocyte Research Laboratory, Department of Hematology, Copenhagen University Hospital, Rigshospitalet, Denmark. lene.udby@rh.regionh.dk
authors.forename: Lene
authors.initials: L
authors.lastname: Udby
authors.forename: Anders H
authors.initials: AH
authors.lastname: Johnsen
authors.forename: Niels
authors.initials: N
authors.lastname: Borregaard
mesh_terms: D000818:Animals; D002417:Cattle; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006098:Granulocytes / Q000378:metabolism; D006736:Horses; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D009961:Orosomucoid / Q000378:metabolism*; D011817:Rabbits; D012471:Salivary Proteins and Peptides / Q000302:isolation & purification / Q000378:metabolism*; D029589:Seminal Plasma Proteins / Q000097:blood* / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013045:Species Specificity
chemical_list: C048566:A1BG protein, human; C489926:CRISP3 protein, human; C489927:Crisp3 protein, mouse; D006023:Glycoproteins; D007136:Immunoglobulins; D009961:Orosomucoid; D012471:Salivary Proteins and Peptides; D029589:Seminal Plasma Proteins