title: Identification of dipeptidyl peptidase IV as the antigen of a monoclonal anti-prostasome antibody.
abstract: BACKGROUND
  Our purpose was to elucidate the identity of an antigen of a monoclonal antibody against prostasomes, which are prostate-derived organelles occurring freely in human semen.
  
  
  METHODS
  Monoclonal antibodies against prostasomes were generated by intrasplenic immunization to allow better characterization of the prostasomes. One third of the resulting antibodies bound to a 110-kDa prostasomal protein on Western blots.
  
  
  RESULTS
  The antigen was purified from seminal prostasomes by anion exchange chromatography and gel electrophoresis. After in-gel digestion and amino-acid sequence analysis of selected peptides, it was identified as dipeptidyl peptidase IV (DPP IV), EC 3.4.14.5, also known as T-cell-activating antigen CD26. No DPP IV could be detected in the supernatant obtained after preparative ultracentrifugation of the prostasomes.
  
  
  CONCLUSIONS
  DPP IV/CD26 is structurally bound to prostasomes rather than being free in seminal fluid. This enzyme may play a critical role in the promoting effect of prostasomes on forward motility of spermatozoa.
authors.affiliation: Department of Human Anatomy, Biomedical Centre, Uppsala, Sweden.
authors.forename: S P
authors.initials: SP
authors.lastname: Schrimpf
authors.forename: U
authors.initials: U
authors.lastname: Hellman
authors.forename: L
authors.initials: L
authors.lastname: Carlsson
authors.forename: A
authors.initials: A
authors.lastname: Larsson
authors.forename: G
authors.initials: G
authors.lastname: Ronquist
authors.forename: B O
authors.initials: BO
authors.lastname: Nilsson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000941:Antigens / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D015153:Blotting, Western; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D018819:Dipeptidyl Peptidase 4 / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008297:Male; D051379:Mice; D008970:Molecular Weight; D015388:Organelles / Q000201:enzymology* / Q000276:immunology; D011467:Prostate / Q000201:enzymology* / Q000276:immunology / Q000648:ultrastructure; D012661:Semen / Q000276:immunology; D017421:Sequence Analysis; D013154:Spleen / Q000276:immunology