title: Development of a monoclonal antibody specific to the endonuclease domain of the human LINE-1 ORF2 protein.
abstract: BACKGROUND
  LINE-1 (L1) retrotransposons are common occupants of mammalian genomes representing about a fifth of the genetic content. Ongoing L1 retrotransposition in the germ line and somatic tissues has contributed to structural genomic variations and disease-causing mutations in the human genome. L1 mobilization relies on the function of two, self-encoded proteins, ORF1 and ORF2. The ORF2 protein contains two characterized domains: endonuclease and reverse transcriptase.
  
  
  RESULTS
  Using a bacterially purified endonuclease domain of the human L1 ORF2 protein, we have generated a monoclonal antibody specific to the human ORF2 protein. We determined that the epitope recognized by this monoclonal antibody includes amino acid 205, which is required for the function of the L1 ORF2 protein endonuclease. Using an in vitro L1 cleavage assay, we demonstrate that the monoclonal anti-ORF2 protein antibody partially inhibits L1 endonuclease activity without having any effect on the in vitro activity of the human AP endonuclease.
  
  
  CONCLUSIONS
  Overall, our data demonstrate that this anti-ORF2 protein monoclonal antibody is a useful tool for human L1-related studies and that it provides a rationale for the development of antibody-based inhibitors of L1-induced damage.
authors.affiliation: Department of Structural and Cellular Biology, Tulane School of Medicine, Tulane Cancer Center, and Tulane Center for Aging, New Orleans, LA 70112 USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Sokolowski
authors.affiliation: Department of Biology, Xavier University, 1 Drexel Drive, Box 85, New Orleans, LA 70125-7918 USA.
authors.forename: Cecily B
authors.initials: CB
authors.lastname: DeFreece
authors.affiliation: Department of Epidemiology, Tulane School of Public Health, Tulane Cancer Center, New Orleans, LA 70112 USA.
authors.forename: Geraldine
authors.initials: G
authors.lastname: Servant
authors.affiliation: Department of Structural and Cellular Biology, Tulane School of Medicine, Tulane Cancer Center, and Tulane Center for Aging, New Orleans, LA 70112 USA.
authors.forename: Kristine J
authors.initials: KJ
authors.lastname: Kines
authors.affiliation: Department of Structural and Cellular Biology, Tulane School of Medicine, Tulane Cancer Center, and Tulane Center for Aging, New Orleans, LA 70112 USA.
authors.forename: Dawn L
authors.initials: DL
authors.lastname: deHaro
authors.affiliation: Department of Structural and Cellular Biology, Tulane School of Medicine, Tulane Cancer Center, and Tulane Center for Aging, New Orleans, LA 70112 USA.
authors.forename: Victoria P
authors.initials: VP
authors.lastname: Belancio
keywords: Endonuclease; In vitro assay; L1; L1 antibody; LINE-1; ORF2; Retrotransposition