Canut H, Carrasco A, Galaud J P, Cassan C, Bouyssou H, Vita N, Ferrara P, Pont-Lezica R
Signaux et Messages Cellulaires chez les Végétaux, UMR 5546 CNRS, Université Paul Sabatier, Toulouse, France.
Plant J. 1998 Oct;16(1):63-71. doi: 10.1046/j.1365-313x.1998.00276.x.
The heptapeptide Tyr-Gly-Arg-Gly-Asp-Ser-Pro containing the sequence Arg-Gly-Asp (RGD--the essential structure recognised by animal cells in substrate adhesion molecules) was tested on epidermal cells of onion and cultured cells of Arabidopsis upon plasmolysis. Dramatic changes were observed on both types of cells following treatment: on onion cells, Hechtian strands linking the cell wall to the membrane were lost, while Arabidopsis cells changed from concave to convex plasmolysis. A control heptapeptide Tyr-Gly-Asp-Gly-Arg-Ser-Pro had no effect on the shape of plasmolysed cells. Protoplasts isolated from Arabidopsis cells agglutinate in the presence of ProNectinF, a genetically engineered protein of 72 kDa containing 13 RGD sequences: several protoplasts may adhere to a single molecule of ProNectinF. The addition of the RGD-heptapeptide disrupted the adhesion between the protoplasts. Purified plasma membrane from Arabidopsis cells exhibits specific binding sites for the iodinated RGD-heptapeptide. The binding is saturable, reversible, and two types of high affinity sites (Kd1 approximately 1 nM, and Kd2 approximately 40 nM) can be discerned. Competitive inhibition by several structurally related peptides and proteins noted the specific requirement for the RGD sequence. Thus, the RGD-binding activity of Arabidopsis fulfils the adhesion features of integrins, i.e. peptide specificity, subcellular location, and involvement in plasma membrane-cell wall attachments.
含有精氨酸 - 甘氨酸 - 天冬氨酸序列（RGD，动物细胞在底物黏附分子中识别的基本结构）的七肽酪氨酸 - 甘氨酸 - 精氨酸 - 甘氨酸 - 天冬氨酸 - 丝氨酸 - 脯氨酸，在洋葱表皮细胞和拟南芥培养细胞质壁分离时进行了测试。处理后，在这两种类型的细胞上均观察到显著变化：在洋葱细胞上，连接细胞壁和细胞膜的赫氏带消失，而拟南芥细胞从凹形质壁分离变为凸形质壁分离。对照七肽酪氨酸 - 甘氨酸 - 天冬氨酸 - 甘氨酸 - 精氨酸 - 丝氨酸 - 脯氨酸对质壁分离细胞的形状没有影响。从拟南芥细胞分离的原生质体在ProNectinF存在下会凝集，ProNectinF是一种含有13个RGD序列的72 kDa基因工程蛋白：几个原生质体可能会黏附到单个ProNectinF分子上。添加RGD七肽会破坏原生质体之间的黏附。从拟南芥细胞纯化的质膜对碘化RGD七肽表现出特异性结合位点。这种结合是可饱和的、可逆的，并且可以识别出两种高亲和力位点（Kd1约为1 nM，Kd2约为40 nM）。几种结构相关的肽和蛋白质的竞争性抑制表明对RGD序列有特定要求。因此，拟南芥的RGD结合活性符合整联蛋白的黏附特征，即肽特异性、亚细胞定位以及参与质膜 - 细胞壁附着。
