^<35>S-Methionine Incorporates Differentially into Polypeptides across Leaves of Spinach (Spinacia oleracea)

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概要

• 論文の詳細を見る

• The distribution of proteins across leaves may have significant impact on optimal photosynthetic performance of leaves, however little is known about the distribution of proteins and protein synthesis across C_3 leaves. We report here a detailed investigation of ^<35>S-methionine incorpora-tion into polypeptides and the steady-state polypeptide pro-files at different leaf depths across spinach leaves. About 10 highly incorporating polypeptides (three with apparent molecular masses of 23 kDa, 21 kDa and 17 kDa were especially dominant) were detected in a few me-dial leaf sections. These highly incorporating polypeptides were soluble proteins, except for the 17 kDa polypeptide, which was associated with thylakoid membranes. All of the highly incorporating polypeptides were nuclearly encoded. Light significantly enhanced ^<35>S-methionine incorporation into the highly incorporating polypeptides in "sun" grown leaves, but not in "shade" grown leaves. Microautoradiography showed that the highly incorporating polypeptides were associated mainly with the phloem tissue. A specific identity or function for the polypeptides is not known. The concentration of most polypeptides on an areal basis appeared to increase with leaf depth from the adaxial leaf surface, reaching a maximum around 25% of the leaf depth, and then declined gradually towards the abaxial surface. The periphery of cells exhibited high levels of ^<35>S-methionine incorporation, and microautoradiography showed that the label was mainly located in the symplast. In general, polypeptides exhibited higher rates of ^<35>S-methionine incorporation in the palisade mesophyll than in the spongy mesophy, probably due to cytoplasmic density and light. The data show that it may be possible to study vascular bundle proteins using paradermal leaf sections. In addition, we now can investigate how factors such as light or CO_2 might control protein distribution across leaves, and further explore the complex interactions among photo-synthesis, leaf anatomy, and light.

• 日本植物生理学会の論文

著者

• Sun J

  Univ. Wyoming Wy Usa

• Sun Jindong

  Department Of Botany University Of Wyoming

• NISHIO John

  Department of Botany, University of Wyoming

• Vogelmann Thomas

  Department of Botany, University of Wyoming

• Vogelmann Thomas

  Department Of Botany University Of Wyoming

• Nishio J

  Univ. Wyoming Wy Usa

• Nishio John

  Department Of Botany University Of Wyoming

関連論文

• Why Abaxial Illumination Limits Photosynthetic Carbon Fixation in Spinach Leaves
• Green Light Drives CO_2 Fixation Deep within Leaves
• ^S-Methionine Incorporates Differentially into Polypeptides across Leaves of Spinach (Spinacia oleracea)

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