The eEFlA gene family is differentially expressed in maize endosperm

eEF1A appears to be a multifunctional protein in eukaryotes, where it serve s as a protein synthesis factor as well as a cytoskeletal protein. In maize endosperm, the eEF1A concentration is highly correlated with lysine conten t, and eEF1A synthesis is increased in opaque2 mutants compared to wild typ e. To investigate the basis for the increased synthesis of eEF1A in opaque2 , we characterized the genes encoding this protein and measured their relat ive level of expression in endosperm and other tissues. Maize contains 10 t o 15 eEF1A genes that are nearly identical in nucleotide and amino acid seq uences. However, these genes can be distinguished based on their 3' non-cod ing sequences, which are less conserved. By screening endosperm and seedlin g cDNA libraries, we show that most of the maize eEF1A genes are expressed, and the relative level of their transcripts varies in different tissues. A t least five genes are transcribed in the endosperm, and two account for ca . 80% of the RNA transcripts. The expression of several genes is enhanced i n opaque2 endosperm, although the significance of this is unclear.