Auxiliary subunit of the NatA N-alpha-acetyltransferase complex. Required for male gametocyte development, embryogenesis, suspensor development and the formation of the quiescent center (QC) in the root meristem (PubMed:27385766, PubMed:27610925). Involved in plant immunity through the regulation of SNC1 stability (PubMed:25966763). Required for embryo development (PubMed:15266054). Part of the NatA complex. Associates with ribosomes. Interacts with NAA10. A number of isoforms are produced. According to EST sequences. Expressed in leaves, roots, shoots and flowers. Down-regulated upon abscisic acid treatment. Embryo lethal when homozygous.