Interactions between MAGE and EID Family Proteins Figure 6. Interplay between MAGE and EID proteins in transcription activation system. (A) Effect of transfected FLAG-NSE4b and S-tagged MAGEG1 on transcriptional activation by SF-1 in HEK293 cells. ‘‘26’’ indicates twice the concentration of MAGEG1 plasmid used in transfections. (B) Effects of FLAG-tagged EID1 or NSE4b on transcriptional activation by different MAGE proteins. The reporter activity in each column is normalised to the activity with nuclear receptor but with neither MAGE nor EID (column 2). Results show mean 6 SEM of 3–5 independent transfections. doi:10.1371/journal.pone.0017270.g006 between MAGEG1 and NSE4b. In our experimental system, we think that this transcriptional activation most likely results from a binary ‘‘free’’ complex of NSE4b and MAGEG1. However it raises the question of whether it can also occur in the context of the SMC5-6 complex. This would indicate a novel role for the SMC5-6 complex in transcriptional activation. Further studies are required to resolve this issue. The evolutionary diversification of the MAGE protein family is remarkable. There is only a single member in fungi, insects [22], birds [23], fish and plants [24], and its most likely function is as part of the SMC5-6 complex. In non-placental mammals there is one member in platypus and two in opossum. In contrast, in placental mammals, there are 33 (+22 pseudogenes) in man, a similar number in mouse and even more in elephants (JP, PLoS ONE | www.plosone.org 9 February 2011 | Volume 6 | Issue 2 | e17270