CHARACTERIZATION OF THE TRITICUM-DURUM DESF CHLOROFORM-METHANOL-SOLUBLE PROTEIN FAMILY

The CM (chloroform-methanol-soluble) proteins are low-molecular-weight cysteine-rich proteins that are found in wheat and barley endosperms. A cDNA clone encoding a Triticum durum (T. dorum) CM3 protein has bee n isolated from a mid-maturation seed cDNA library. The T. durum CM3 p rotein is synthesized as a precursor including a signal peptide (SP) o f 25 residues. Northern blot analysis showes that in developing seed t he highest level of CM3 protein mRNA is detected at mid-maturation. Th e hybridization patterns obtained by Southern blot analysis indicated that T. durum CM proteins are encoded by a small multigene family. The similarity between the wheat and barley CM proteins encoded by homolo gous chromosomes is much higher than that between each of the three me mbers of the T. durum family. All CM proteins contain ten cysteine res idues organized in a conserved cysteine motif.