Molecular cloning of 11S globulin and 2S albumin, the two major seed storage proteins in sesame

Insoluble 11S globulin and soluble 2S albumin, conventionally termed alpha- globulin and beta-globulin, are the two major storage proteins and constitu te 80-90% of total seed proteins in sesame. Two full-length cDNA clones wer e sequenced and deduced to encode sesame 11S globulin and 2S albumin precur sors, respectively. Deduced amino acid composition reveals that 2S albumin, but not 11S globulin, is a sulfur-rich protein. Three abundant polypeptide s of 50-60 kDa were resolved on SDS-PAGE when seed-purified 11S globulin wa s prepared in nonreducing conditions. Immunological analysis suggests that these three polypeptides are encoded by homologous genes. Immunodetection o n the overexpressed protein of the 11S globulin clone in Escherichia coli i ndicates that this clone encodes the precursor protein of one of the three purified 11S globulin polypeptides.