title: Functional characterization of the domains of the bovine binder of SPerm 5 (BSP5) protein.
abstract: BACKGROUND
  Bovine BSP5 is a multifunctional protein primarily involved in sperm capacitation. BSP5 consists of long N-terminal part followed by two similar and highly conserved fibronectin type II domains designated A and B.
  
  
  METHODS
  In order to assess the role of these domains in the sperm binding and capacitation processes, we created recombinant individual domains (N, A, B), series of overlapping domains (NA and AB) and full-length BSP5 in an Escherichia coli expression system. The recombinant constructs were also tested for their ability to interact with ligands such as gelatine, heparin, chondroitin sulphate B and phosphatidylcholine liposomes by affinity chromatography and co-sedimentation studies.
  
  
  RESULTS
  With the exception of the N domain, all recombinant constructs retained gelatine, phosphatidylcholine, heparin and chondroitin sulphate B binding activities. Domain-wise studies showed clearly that AB domain is capable of performing its biological functions as well as the full-length protein, as it was able to potentiate heparin-mediated sperm capacitation.
  
  
  CONCLUSIONS
  These results indicate that the C-terminal domain composed of two Fn2 domains is sufficient and crucial to maintain the biological functions of BSP proteins. The N-terminal part of the protein did not bind to any of known BSP5-ligands including epididymal sperm and did not seem to be required for either sperm binding or sperm capacitation. This study also confirmed that glycosylation is not required for BSP-mediated sperm capacitation or any of the binding characteristics displayed by BSP5.
authors.affiliation: Maisonneuve-Rosemont Hospital Research Centre, Montreal, QC, Canada. prashanth.jois@gmail.com.
authors.forename: Prashanth Sirigeri
authors.initials: PS
authors.lastname: Jois
authors.affiliation: Maisonneuve-Rosemont Hospital Research Centre, Montreal, QC, Canada. genevieve.plante@umontreal.ca.|Department of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Montreal, Quebec, Canada. genevieve.plante@umontreal.ca.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Plante
authors.affiliation: Maisonneuve-Rosemont Hospital Research Centre, Montreal, QC, Canada. therienisabelle@gmail.com.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Thérien
authors.affiliation: Maisonneuve-Rosemont Hospital Research Centre, Montreal, QC, Canada. puttaswamy.manjunath@umontreal.ca.|Department of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Montreal, Quebec, Canada. puttaswamy.manjunath@umontreal.ca.|Department of Medicine, Faculty of Medicine, University of Montreal, Quebec, Canada. puttaswamy.manjunath@umontreal.ca.|Maisonneuve-Rosemont Hospital Research Center, 5415 l'Assomption blvd, Montreal, QC, H1T 2 M4, Canada. puttaswamy.manjunath@umontreal.ca.
authors.forename: Puttaswamy
authors.initials: P
authors.lastname: Manjunath
mesh_terms: D000818:Animals; D002417:Cattle; D003871:Dermatan Sulfate / Q000378:metabolism; D006493:Heparin / Q000378:metabolism; D008297:Male; D010713:Phosphatidylcholines / Q000378:metabolism; D011485:Protein Binding; D029589:Seminal Plasma Proteins / Q000378:metabolism*; D013075:Sperm Capacitation / Q000502:physiology*
chemical_list: D010713:Phosphatidylcholines; D029589:Seminal Plasma Proteins; D003871:Dermatan Sulfate; D006493:Heparin