Plant Molecular Biology 18: 423--427, 1992. © 1992 Kluwer Academic Publishers. Printed in Belgium. Update section Short communication 423 Nucleotide sequence of a eDNA coding for the barley seed protein CMa: an inhibitor of insect s-amylase Soren K. Rasmussen and Anette Johansson Plant Biology Section, Environmental Science and Technology Department, Riso National Laboratory, DK-4000 Roskilde, Denmark Received 16 July 1991; accepted in revised form 2 October 1991 Key words: Hordeum vulgare L., CM protein, wheat Abstract The primary structure of the insect e-amylase inhibitor CMa of barley seeds was deduced from a full- length cDNA clone pc43F6. Analysis of RNA from barley endosperm shows high levels 15 and 20 days after flowering. The cDNA predicts an amino acid sequence of 119 residues preceded by a signal pep- tide of 25 amino acids. Ala and Leu account for 55 ~o of the signal peptide. CMa is 60-85 ~o identical with e-amylase inhibitors of wheat, but shows less than 50?o identity to trypsin inhibitors of barley and wheat. The 10 Cys residues are located in identical positions compared to the cereal inhibitor family with a Pro-X-Cys motif present in all. Albumins of cereal endosperm include inhibitors of trypsin and e-amylases. They were originally characterized by their solubility in a mixture of chloroform and methanol and therefore desig- nated as CM proteins. Five of these proteins from barley seeds, CMa-e, have been characterized: they show a Mr of approximately 13 000. Further- more, the N-terminal sequence has been deter- mined for all of them showing limited sequence similarity [2, 9, 15]. The complete amino acid sequence of CMe, an inhibitor of trypsin, has been established [11]. A cDNA clone predicts the amino acid sequence of the trypsin inhibitor CMd [7]. Sequences of barley CMa-e proteins show similarity with inhibitors of trypsin/e- amylase from wheat and rye, forming the cereal inhibitor superfamily of proteinases and c~- amylases as reviewed in [5, 13]. The barley CMa was shown to inhibit e-amylase from Tenebrio melitor, mealworm beetle [2]. Larvae of this in- sect can cause considerable losses during barley grain storage. A full-length cDNA clone, pc43F6, coding for the CMa e-amylase inhibitor, was collected in a library constructed using mRNA isolated from barley seeds, cv. Bomi [8]. The seeds were bar- The nucleotide sequence data reported will appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession number X59264.