黑素合成酶是黑素小体成熟所必需蛋白。它们从TGN转运到黑素小体的机制已较明确，但在TGN内转运并启动分拣的机制仍不清楚。ABCB6是我们于2013年率先鉴定的一个色素代谢相关蛋白。近期我们又发现：在黑素细胞TGN内ABCB6通过与下游RUTBC1相互作用而调控黑素合成酶顺行转运。RUTBC1是一个Rab33B的GTP酶活化蛋白，Rab33B存在于TGN。因此推测：TGN内Rab33B可能通过与RUTBC1相互作用而调控黑素合成酶转运。本项目拟采用CLSM技术等对Rab33b/Rutbc1/Abcb6稳定沉默的黑素细胞进行分组研究，明确TGN内Rab33B在RUTBC1下游调控黑素合成酶转运；探明TGN内Rab33B互作蛋白，阐明其作用机制。本项目的完成将丰富ABCB6-RUTBC1调控黑素合成酶转运的机制，对系统理解TGN功能具有重要的理论意义，并为其它LROs研究提供参考依据。

Melanosomes are members of the well-documented family of LROs. Melanogenic enzymes are required for melanosome mature. There is much knowledge about melanogenic enzymes trafficking from the TGN to melanosomes in melanocytes, but they transport within the TGN is still poorly understood. ABCB6, a novel agent involved in the process of skin pigmentation, was identified from patients with dyschromatosis universalis hereditaria by our team in 2013. Our recent experimental findings indicated that ABCB6 regulates the anterograde transport of melanogenic enzymes through its interaction with RUTBC1 in the TGN. Some data show that RUTBC1 functions as a GTPase-acitvating Protein for Rab33B and Rab33B is present in the TGN. So, these data suggest that Rab33B might regulate the trafficking of melanogenic enzymes through its interaction with RUTBC1 in the TGN. To verify this hypothesis, we will demonstrate that Rab33B acts downstream of ABCB6-RUTBC1 in regulating the trafficking of melanogenic enzymes in the TGN using confocal laser scanning microscope and co-immunoprecipitation technology. At last, we will find out the Rab33B ineracting protein in the TGN by co-immunoprecipitation technology and mass spectrometric analysis. The mechanism of melanogenic enzymes transport in the TGN will be further understood and it will shed new light on other LROs when we accomplish this project.