橡胶生物合成以蔗糖为原料、在特化的乳管细胞中进行。乳管细胞中蔗糖的降解效率是决定胶乳代谢活性、影响橡胶产量的关键因素。在前期研究中，我们分离和鉴定了负责乳管蔗糖降解利用的中/碱性转化酶（A/N-Inv）HbNIN2。拟南芥根中，磷脂酰肌醇磷酸激酶（PIP5K）和14-3-3蛋白能直接同A/N-Inv互作并调控其酶活性，但不清楚在不同植物或不同组织（或细胞）中是否有新的A/N-Inv互作蛋白或存在不同的调控模式。本项目以HbNIN2为靶标，将酵母双杂交、免疫共沉淀和双分子荧光互补技术相结合筛选和鉴定胶乳中HbNIN2的互作蛋白，同时利用体外酶学测定和胶乳分析法，研究互作蛋白对HbNIN2的酶学调控模式，以及这种调控与胶乳转化酶和胶乳代谢调控的关系。研究结果将有助于阐明橡胶树乳管蔗糖降解调控的分子机制，拓展植物A/N-Inv分子调控研究的领域，为胶乳代谢人工调控新技术的研发提供理论指导。

In rubber tree (Hevea brasiliensis), natural rubber biosynthesis occurs in a specialized cell type called laticifers, with sucrose as the precursor molecule. In the laticifers, the efficiency of sucrose catabolism is a rate-limiting step affecting latex (cytologically, the cytoplasm of laticifers) metabolism and rubber productivity. Previously, an alkaline/neutral invertase (A/N-Inv), HbNIN2, was identified as the key enzyme responsible for sucrose catabolism in the laticifers. In the roots of Arabidopsis, phosphatidylinositol monophosphate 5-kinase (PIP5K) and 14-3-3 protein directly interact with A/N-Invs and regulate their enzymatic activity. It remains to learn whether there are new proteins interacting with A/N-Invs or novel regulation modes in different plant species or different tissue/cell types. This proposal aims to screen and identify the HbNIN2-interacting proteins with combining the techniques of Y2H, CoIP and BiFC, investigate their regulations on the enzymatic properties of HbNIN2, and learn the correlation of such regulations in the regulating latex invertase and latex metabolism. The results expected will help elucidate the molecular mechanisms underlying sucrose catabolism in the laticifers of rubber tree, expand the researches in the molecular regulation of A/N-Invs in plants, and give hints to developing novel techniques to stimulate latex production.