Otoconin 90 (OC90)

AF-5 contains an open reading frame beginning within RTVL-H sequences and continuing with a region from an adjacent gene that encodes 2 domains homologous to PLA2. The authors designated the adjacent gene PLA2L (PLA2-like gene). PLA2s generally have only a single PLA2 domain; neither PLA2L phospholipase domain could be classified definitively as a member of a known PLA2 group. Using Southern blots, the authors determined that the RTVL-H element is a normal part of the PLA2L locus in humans. Northern blot analysis revealed that PLA2L is expressed only in teratocarcinoma cell lines.Although OC90 has a predicted molecular mass of 49 kD and pI of 4.4, it has an apparent molecular mass of 83 kD and pI of 2.9. The authors attributed the discrepancy to nonhomogeneous glycosylation.