Primary maize reference (Springer et al. 2002) describing the three maize Enhancer-of-zeste-like genes Mez1/Mez2/Mez3 (Mez1 = EZ1/MEZ1), their conserved PcG domains, and tissue expression; Mez transcripts were detected in all tissues tested. PcG proteins act in developmental and epigenetic regulation of gene expression, and the cross-kingdom conservation of E(z)/esc homologs indicates a conserved role in repressing gene expression.

InterPro-to-GO mappings (IPR045318 EZH1/2-like) assign histone methyltransferase activity and chromatin remodeling to EZ1.

E(z)/EZH-family functions (chromatin binding, heterochromatin formation) are conserved across the PANTHER PTHR45747 phylogenetic group and propagated to EZ1 by IBA.

SwissProt keyword-derived (SPKW) annotation present in the Sept 2025 goa_uniprot_gcrp snapshot but removed from the current GOA release after GOA retired the keyword2GO pipeline for cellular organisms.

For EZ1, the keyword "Methyltransferase"/"Transferase" mapped to the generic process "methylation" (GO:0032259), which drops the substrate; the substrate-specific histone H3K27 methyltransferase activity is already annotated, so the generic process term is redundant.

Annotations transferred from the Arabidopsis (SWN/CLF) and rice E(z) orthologs to maize EZ1, including histone H3K27 methyltransferase activity, heterochromatin formation, epigenetic negative regulation, and developmental (flowering/photoperiod) processes.

Nuclear localization, PcG protein complex membership, and EC-derived histone H3K27 trimethyltransferase activity assigned to EZ1 by combined IEA methods.

Confirms target identity: maize Mez1 is one of three E(z)-like genes (Mez1/Mez2/Mez3); Mez1 is the clf-like homolog while Mez2/Mez3 are EZA1/SWN-like (Springer et al. 2002, doi:10.1104/pp.010742), matching UniProt Q8S4P6 as an EZH1/2-like histone-lysine methyltransferase.

EZ1/MEZ1 is most strongly supported to be a SAM-dependent histone lysine methyltransferase acting on H3K27, consistent with its EC assignment in UniProt and its E(z)-class SET domain conservation; plant PRC2 deposits H3K27 methylation establishing a repressive chromatin state at target loci.

PRC2 is a chromatin-associated nuclear complex; most PRC2 proteins localize to the nucleus and form multi-subunit complexes, supporting EZ1/MEZ1 nuclear, on-chromatin function within PRC2-like assemblies.

Maize H3K27me3 marks define facultative heterochromatin attributed to the E(z)/PRC2 pathway; Mez2/Mez3 mutants reduce H3K27me3 at a subset of loci (partial redundancy); Mez1 is uniquely imprinted among the three homologs; direct Mez1 loss-of-function and in vitro biochemistry on the maize protein were not available in the retrieved corpus.