Key message
GluA and GluB-4/5 glutelin subfamilies are mainly localized to outer region of the endosperm, particularly in its ventral side, in rice grain, but GluC is localized to throughout the endosperm.
Abstract
The major seed storage protein in rice (
Oryza sativa
) is glutelin, which forms a vacuole-derived protein body type-II. Glutelins are encoded by multiple genes, and generally comprise four protein subfamilies, namely, GluA, GluB, GluC, and GluD: however, the localization pattern of glutelin in rice grains remains obscure. In this study, we investigated the localization pattern of five subtypes of the glutelin protein in rice grains using glutelin-subtype specific antibodies. Immunoblot analysis against sequentially polished rice flour fractions from three crop years and seven japonica rice varieties revealed that GluA was strongly localized in the outer region of the endosperm, including the subaleurone layer, whereas GluC was distributed throughout the endosperm. Among the glutelin subtypes, GluA was mostly found in the outer region of the rice grain, followed by GluB-4/5, GluB-1, GluD, and GluC. Immunofluorescence labeling microscopy analysis using immature rice seeds clearly revealed that the localization pattern of GluC and GluD was completely different from that of GluA and GluB. Expression levels of all glutelins, particularly GluA, GluB-1, and GluB-4/5, were stronger on the ventral than dorsal side in rice grains. These results provide strong and consistent evidence that glutelins localize to the rice grain in a subfamily-dependent manner.
Electronic supplementary material
The online version of this article (10.1007/s11103-019-00855-5) contains supplementary material, which is available to authorized users.
The temporomandibular joint (TMJ) articular discs were removed from female Sprague-Dawley rats 3, 5, 10, 32, 90 and 130 weeks of age. Glycosaminoglycans (GAGs) were extracted from the discs by heat treatment, alkali treatment and digestion with Pronase E, and purified by precipitation with cetylpyridinium chloride and ethanol. The concentration of total GAG was highest in the 3 week extracts and tended to decrease with age. Dermatan sulphate was the predominant GAG detected in all age groups along with chondroitin sulphate, hyaluronic acid and heparan sulphate. The disaccharides obtained from chondroitin sulphate were delta Di-4S, delta Di-6S and delta Di-0S, with delta Di-4S being the predominant isomer followed by delta Di-6S for all ages of all the GAG examined. The concentration of chondroitin sulphate showed a decrease with age. Quantitative changes of GAG with age may be related to functional changes in TMJ discs.
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