title: The maize brittle 1 gene encodes amyloplast membrane polypeptides.
abstract: A chimeric protein, formed of 56 amino acids from the carboxy terminus of the maize (Zea mays L.) wild-type Brittle1 (Bt1) protein fused to the glutathione-S-transferase gene, was synthesized in Escherichia coli, and used to raise antibodies. Following affinity purification, the antibodies recognized a set of 38- to 42-kDa proteins in endosperm from wild-type Bt1 plants, as well as from brittle2, shrunken2 and sugary1 plants, but not in mutant bt1 endosperm. Bt1 proteins were not detected with the preimmune antibodies. A low level of Bt1-specific proteins was detected at 10 d after pollination (DAP) and increased to a plateau at 16 DAP. At the same time, the ratio of slow- to fast-migrating forms of the protein decreased. During endosperm fractionation by differential centrifugation and membrane sedimentation in sucrose gradients, the Bt1 proteins co-purified with the carotenoid-containing plastid membranes. They were localized to amyloplasts by electron-microscopic immunocytochemistry; most of the signal was detected at the plastid periphery. These results are consistent with predictions made from the deduced amino-acid sequence and previous in-vitro experiments that the bt1 locus encodes amyloplast membrane proteins.
authors.affiliation: Laboratory of Genetics, University of Wisconsin, Madison 53706, USA.
authors.forename: T D
authors.initials: TD
authors.lastname: Sullivan
authors.forename: Y
authors.initials: Y
authors.lastname: Kaneko
mesh_terms: D000906:Antibodies; D000918:Antibody Specificity; D002458:Cell Fractionation; D004926:Escherichia coli; D015870:Gene Expression; D008565:Membrane Proteins / Q000235:genetics* / Q000276:immunology; D008854:Microscopy, Electron; D010940:Plant Proteins / Q000235:genetics* / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000235:genetics; D003313:Zea mays / Q000235:genetics* / Q000648:ultrastructure
chemical_list: D000906:Antibodies; D008565:Membrane Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins