HERV-H LTR Associating Protein 1 (HHLA1)

Human endogenous retroviruses (HERVs) are repetitive elements, derived from ancient germline retroviral infections, that have increased in copy number by further rounds of infection, retrotransposition, and/or duplication.

PLA2L is a tripartite fusion transcript expressed from the HERV-H element's promoter and containing exons from a novel gene, HHLA1, and from OC90, a gene encoding an inner ear protein with PLA2 domains. The coding regions of the AF6, -7, and -8 mRNAs are derived only from the HHLA1 gene and encode a predicted 305-amino acid protein. The authors hypothesized that the human HHLA1 and OC90 genes are normally expressed independently from different promoters, and that the intergenic splicing event that generates PLA2L is specific to teratocarcinoma cells.