BACKGROUND Small ROP (also called RAC) GTPases are key factors in polar cell development and in interaction with the environment. ROP-Interactive Partner (RIP) proteins are predicted scaffold or ROP-effector proteins, which function downstream of activated GTP-loaded ROP proteins in establishing membrane heterogeneity and cellular organization. Grass ROP proteins function in cell polarity, resistance and susceptibility to fungal pathogens but grass RIP proteins are little understood. RESULTS We found that the barley (Hordeum vulgare L.) RIPa protein can interact with barley ROPs in yeast. Fluorescent-tagged RIPa, when co-expressed with the constitutively activated ROP protein CA RAC1, accumulates at the cell periphery or plasma membrane. Additionally, RIPa, locates into membrane domains, which are laterally restricted by microtubules when co-expressed with RAC1 and MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1. Both structural integrity of MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1 and microtubule stability are key to maintenance of RIPa-labeled membrane domains. In this context, RIPa also accumulates at the interface of barley and invading hyphae of the powdery mildew fungus Blumeria graminis f.sp. hordei. CONCLUSIONS Data suggest that barley RIPa interacts with barley ROPs and specifies RAC1 activity-associated membrane domains with potential signaling capacity. Lateral diffusion of this RAC1 signaling capacity is spatially restricted and the resulting membrane heterogeneity requires intact microtubules and MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1. Focal accumulation of RIPa at sites of fungal attack may indicate locally restricted ROP activity at sites of fungal invasion.

中文翻译：

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大麦 ROP-Interactive Partner-a 组织成 RAC1 和微管相关的 ROP-GTP 酶激活蛋白 1 依赖性膜域。


背景小ROP（也称为RAC）GTP酶是极细胞发育以及与环境相互作用的关键因素。 ROP 交互伙伴 (RIP) 蛋白是预测的支架蛋白或 ROP 效应蛋白，其在激活的 GTP 负载 ROP 蛋白下游发挥作用，建立膜异质性和细胞组织。草 ROP 蛋白在细胞极性、对真菌病原体的抵抗力和易感性方面发挥作用，但草 RIP 蛋白却知之甚少。结果我们发现大麦 (Hordeum vulgare L.) RIPa 蛋白可以与酵母中的大麦 ROP 相互作用。荧光标记的 RIPa 与组成型激活的 ROP 蛋白 CA RAC1 共表达时，会在细胞外周或质膜处积聚。此外，RIPa 位于膜域中，当与 RAC1 和微管相关 ROP-GTP 酶激活蛋白 1 共表达时，膜域受到微管的横向限制。微管相关 ROP-GTP 酶激活蛋白 1 的结构完整性和微管稳定性都是关键维持 RIPa 标记的膜结构域。在这种情况下，RIPa 也会在大麦和白粉病真菌 Blumeria graminis f.sp 的入侵菌丝的界面处积累。大麦。结论 数据表明，大麦 RIPa 与大麦 ROP 相互作用，并指定具有潜在信号传导能力的 RAC1 活性相关膜域。这种 RAC1 信号传导能力的横向扩散在空间上受到限制，并且由此产生的膜异质性需要完整的微管和微管相关的 ROP-GTP 酶激活蛋白 1。RIPa 在真菌攻击部位的局部积累可能表明真菌入侵部位的 ROP 活性受到局部限制。