Figure 7. Model for Regulation of MEA Imprinting.
MEA methylation is maintained by MET1. In the central cell, DME removes methylation at the −500 bp region and MEA-ISR. MEA protein is produced and forms PcG complexes. After fertilization, MEA-FIE PcG complexes target the paternal allele to maintain its silent state. Maternal MEA continues to be expressed in the endosperm. Gray box, MEA gene; red circles, DNA methylation; helical line, nontranscribed compacted chromatin; straight line, transcribed open chromatin.