Maize profilin isoforms are functionally distinct
Maize profilin isoforms are functionally distinct
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DOI：
10.1105/tpc.12.4.583
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发表时间：
2000-04-01
期刊：
影响因子：
11.6
通讯作者：
Staiger, CJ
中科院分区：
文献类型：
--
作者：
Kovar, DR;Drobak, BK;Staiger, CJ
Profilin是一种肌动蛋白单体结合蛋白，根据条件的不同，它可以引起肌动蛋白细丝的聚合或解聚。在植物中，Profilin由多基因家族编码。在这项研究中，对玉米天然蛋白和重组蛋白的分析表明，存在两类功能不同的Profilin异构体。II类蛋白，包括天然胚乳蛋白和一种新的重组蛋白ZmPRO5，具有与I类蛋白不同的生化特性。与I类Profilin相比，II类Profilin对多聚L-脯氨酸具有更高的亲和力，并隔离更多的单体肌动蛋白。相反，I类Profilin对磷脂酶C对膜磷脂酰肌醇-4，5-二磷酸的抑制作用强于II类Profilin。这些生化特性与II类Profilin比I类Profilin更快地破坏活细胞中肌动蛋白细胞质结构的能力相关。研究发现，两种类型的玉米Profilin的肌动蛋白隔离活性都依赖于游离钙的浓度。我们提出了一个模型，在这个模型中，玉米Profilin通过改变细胞内肌动蛋白聚合物的浓度来响应细胞内钙浓度的变化，这些结果提供了强有力的证据，表明玉米Profilin基因家族至少由两个类别组成，具有不同的生化和活细胞特性，这意味着玉米Profilin亚型在植物中发挥着不同的功能。
Profilin is an actin monomer binding protein that, depending on the conditions, causes either polymerization or depolymerization of actin filaments. In plants, profilins are encoded by multigene families. In this study, an analysis of native and recombinant proteins from maize demonstrates the existence of two classes of functionally distinct profilin isoforms. Class II profilins, including native endosperm profilin and a new recombinant protein, ZmPRO5, have biochemical properties that differ from those of class I profilins. Class II profilins had higher affinity for poly-L-proline and sequestered more monomeric actin than did class I profilins. Conversely, a class I profilin inhibited hydrolysis of membrane phosphatidylinositol-4,5-bisphosphate by phospholipase C more strongly than did a class II profilin. These biochemical properties correlated with the ability of class II profilins to disrupt actin cytoplasmic architecture in live cells more rapidly than did class I profilins. The actin-sequestering activity of both maize profilin classes was found to be dependent on the concentration of free calcium. We propose a model in which profilin alters cellular concentrations of actin polymers in response to fluctuations in cytosolic calcium concentration, These results provide strong evidence that the maize profilin gene family consists of at least two classes, with distinct biochemical and live-cell properties, implying that the maize profilin isoforms perform distinct functions in the plant.