| Abstract: | Proteins are found as integral components of starch granule structure. The starch granule-bound proteins from the endosperm of nonmutant (normal) and waxy (glutinous) cereals were extracted and subsequently separated by electrophoresis on denaturing SDS-polyacrylamide gels. The silver stained gels revealed that for cereals the waxy protein (starch granule-bound starch synthase) was approximately 60 kD. The cereals containing the waxy mutation do not show this protein. Compared to the nonmutant genotypes of other cereals, the waxy protein of barley, Hordeum vulgare is greatly diminished. Based on this observation, there may be reason to suspect that starch synthesis in barley varies from that of other cereals. There are minor homologous proteins among the cereals studied, including, maize, teosinte, rice, millet, sorghum, and barley. Starch granules from all cereal genotypes studied exhibited a minor protein at 68 kD. Most (81%) genotypes showed a 65 kD protein, which may correspond to a minor isozyme of starch granule-bound starch synthase. Minor proteins occurred at 70 kD and 72 kD in 71% and 57% of the genotypes studied, respectively. The minor proteins could be isozymes of starch granule-bound starch synthase or the proposed granule-bound forms of branching enzyme and oligosaccharide synthase. |
