Department of Botany, University of California, 94720, Berkeley, California, USA.
Planta. 1974 Sep;119(3):193-206. doi: 10.1007/BF00429044.
Protein release from gibberellic acid-treated aleurone cells of barley (Hordeum vulgare L.) was followed in pulse-chase experiments with radioactively labelled amino acids. After a 10-min pulse of [(3)H]leucine or [(3)H]tryptophan, label was incorporated into trichloroacetic-acid (TCA)-insoluble material; some of this was released into the incubation medium during a chase with carrier amino acid. This relase of TCA-insoluble material into the incubation medium had no appreciable lag period. Precipitation with rabbit-anti-α-amylase antibody of the radioactivity released from aleurone layers into the medium during chasing indicates that as much as 70% of the radioactivity present is α-amylase. Aleurone cell homogenates were fractionated by differential centrifugation after pulsing with labelled amino acids. Radioactivity in TCA-insoluble materials was distributed equally among all sediment fractions indicating that no specific accumulation of label occurred. Tissue was also fractionated after labelling with a pulse of [(3)H]tyrosine and [(14)C]-tryptophan, and the distribution of radioactivity in various fractions also showed that no preferential sedimentation of label occurred. Altogether, no experimental evidence could be found to support the hypothesis that proteins are released from aleurone cells via discrete secretory organelles.
用放射性标记氨基酸进行脉冲追踪实验，研究了赤霉酸处理的大麦糊粉层细胞的蛋白质释放。用 [(3)H]亮氨酸或 [(3)H]色氨酸进行 10 分钟脉冲标记后，标记物掺入三氯乙酸（TCA）不溶性物质中；在载体氨基酸的追赶过程中，其中一些被释放到孵育培养基中。TCA 不溶性物质释放到孵育培养基中没有明显的滞后期。用兔抗α-淀粉酶抗体沉淀在追赶过程中从糊粉层释放到培养基中的放射性表明，存在的放射性的多达 70%是α-淀粉酶。用标记氨基酸脉冲处理后，通过差速离心对糊粉层细胞匀浆进行分级。TCA 不溶性物质中的放射性在所有沉淀级分中均匀分布，表明没有发生特定的标记积累。用 [(3)H]酪氨酸和 [(14)C]-色氨酸的脉冲标记后，组织也进行了分级，各种级分中的放射性分布也表明没有发生标记的优先沉降。总的来说，没有实验证据支持蛋白质通过离散的分泌细胞器从糊粉层细胞中释放的假说。
