FOB1 is a host gene found in certain fungal organisms whose protein encoded product is an integrase (INT) like enzyme of 510-535 residues that is involved in the rDNA metabolism (Dlakic 2002). For simplicity´s sake the figure below shows the genomic structure without introns.
There are two complementary classifications for FOB1. Based on sequence this gene can be classified as a member of the pool of DDE transposases (TRs) and (INTs). Within this scenario, phylogenetic inference suggests that FOB1 is related to the GINGER2 transposons (Bao et al. 2010) and the SCAN/KRAB genes (which are domesticated GINGER2 transposons). On the other hand, in 2002 FOB1 a protein involved in the rDNA metabolism of Saccharomyces was related to retroviral INTs (Dlakic 2002). Based on INT-like structural potential similarities, the INT coded by FOB1 is member of the Retroviral Integrase Superfamily (Nowotny 2009) of nucleic acid-processing enzymes involved in; a) selfish evolution; b) replication and repair of DNA; c) recombination and gene fusion; d) RNA-mediated gene silencing; and e) oncogenesis.