Characterization of the Major Protein Component from Aleurone Cells of Barley (<i>Hordeum vulgare</i>L.)

Abstract

Comparison of the SDS-PAGE patterns of salt-soluble proteins from aleurone protoplasts, enriched aleurone layers prepared by pearling, and isolated embryos of mature barley showed three groups of bands that reacted with antiserum raised against the 7S globulins of oat embryos. These had Mrs of about 50 000, 40 000 and 25 000. The enriched aleurones also contained a third group of immunoreactive bands (Mr about 70 000), which did not co-purify when the proteins were fractionated by ammonium sulphate precipitation, ion exchange chromatography and immunoaffinity chromatography. The purified protein gave a single sharp peak on RP-HPLC, and contained a fourth minor group of subunits of Mr about 20 000, in addition to those of Mrs about 50 000, 40 000 and 25 000. The holoprotein and the ‘major groups’ of subunits all had similar major N-terminal amino acid sequences which were related to the N-terminal amino acid sequences of pea and bean vicilins, and to sequences in the putative N-terminal regions of the mature 7S α1-globulins of cottonseed, confirming the homology with these groups of proteins.