Pertl H, Gehwolf R, Obermeyer G
Molecular Plant Physiology, Div. Allergy and Immunology, Dept. Molecular Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria.
Plant Biol (Stuttg). 2005 Mar;7(2):140-7. doi: 10.1055/s-2005-837583.
Proteins of the 14-3-3 family show a broad range of activities in plants, depending on their localisation in different cellular compartments. Different organelle membranes of pollen grains and pollen tubes of Lilium longiflorum Thunb. were separated simultaneously using optimised discontinuous sucrose density centrifugation. The obtained organelle-enriched fractions were identified as vacuolar, Golgi, endoplasmic reticulum and plasma membranes, according to their marker enzyme activities, and were assayed for membrane-bound 14-3-3 proteins by immunodetection. 14-3-3 proteins were detected in the cytoplasm as well as in all obtained organelle fractions but were also released into the extracellular medium. In pollen grains, much more plasma membrane-bound 14-3-3 proteins were detected than in the PM-enriched fraction of pollen tubes, whereas the level of Golgi- and ER-associated 14-3-3 proteins was similar in pollen grains and tubes. This shift in the localisation of membrane-associated 14-3-3 proteins is probably correlated with a change in the major function of 14-3-3 proteins, e.g., perhaps changing from initiating pollen grain germination by activation of the PM H +-ATPase to recruitment of membrane proteins via the secretory pathway during tube elongation.
14-3-3家族蛋白在植物中表现出广泛的活性，这取决于它们在不同细胞区室中的定位。利用优化的不连续蔗糖密度离心法，同时分离了麝香百合花粉粒和花粉管的不同细胞器膜。根据其标记酶活性，将获得的富含细胞器的组分鉴定为液泡、高尔基体、内质网和质膜，并通过免疫检测法检测膜结合的14-3-3蛋白。在细胞质以及所有获得的细胞器组分中都检测到了14-3-3蛋白，但它们也释放到了细胞外培养基中。在花粉粒中，检测到的质膜结合14-3-3蛋白比花粉管的富含质膜组分中的要多得多，而高尔基体和内质网相关的14-3-3蛋白水平在花粉粒和花粉管中相似。膜相关14-3-3蛋白定位的这种变化可能与14-3-3蛋白主要功能的改变有关，例如，可能从通过激活质膜H +-ATPase启动花粉粒萌发转变为在花粉管伸长过程中通过分泌途径募集膜蛋白。
