Molecular mechanistic properties of a novel N-Ank superfamily member, Ankrd24, its functions and its interplay with BAR domain proteins in modulating membranes topologies and shaping cells

成膜对于建立、维持和改变细胞器和整个细胞的形态至关重要。蛋白质可以直接驱动所需的局部膜拓扑变化，因此引起了人们的极大兴趣。锚蛋白重复序列采用弯曲结构，是蛋白质中最常见的结构特征之一。我们最近提出，主要基于对Ankycorbin的示范研究，新发现的Anyrin重复蛋白的一个子集，我们称之为N-Ank蛋白，使用两亲性α-螺旋和Ankyrin重复序列的组合来感测膜的曲率和成膜。我们建议将这个新的超家族中到目前为止仅被预测的成员Ankrd24定性为假定的膜成形器，以确定其在神经元发育过程中形成树突状树突的功能，研究其与膜成形器bar结构域蛋白家族成员的分子和功能相互作用，并通过综合的生化研究、(超)高分辨率成像和功能分析来揭示Ankrd24用于其功能的分子机制。对Ankrd24分子机械特性和细胞生物学功能的详细描述将揭示Ankrd24与膜相互作用和调节膜拓扑结构的基本原理。对影响N-ANK模块的Ankrd24剪接变体的分析将为深入了解Ankrd24‘S选择性剪接的功能后果以及如何调节N-Ank模块的一般性质提供重要的见解。我们鉴定Ankrd24与另一个不同的膜成形器蛋白质家族的相互作用，进而作为令人兴奋的起点，研究不同的膜拓扑识别和调节蛋白是否以及在多大程度上合作塑造膜和整个细胞。因此，我们将通过全面的生化分析以及高分辨率成像和神经元功能研究来解决这一新概念。总之，研究一个新的N-Ank超家族成员在神经形态发生中的机制和功能作用，并研究其与另一种不同性质的膜成形器的物理和功能相互作用，将为我们理解细胞膜和整个细胞的形态发生开辟重要的新篇章。

Shaping membranes is crucial for establishing, maintaining and changing the morphology of cellular organelles and of entire cells. Proteins that can directly power the required local membrane topology changes thus attract high interest. Ankyrin repeats adopt a curved structure and are one of the most frequently observed structural features in proteins. We recently proposed that, mainly based on the exemplary examination of ankycorbin, a newly discovered subset of ankyrin repeat proteins, which we termed N-Ank proteins, uses a combination of an amphipathic α-helix and ankyrin repeats to sense membrane curvature and to shape membranes. We here propose to characterize a thus far merely predicted member of this novel superfamily, Ankrd24, as putative membrane shaper, to identify its functions in shaping the dendritic arbor of neurons during their development, to address its molecular and functional interplay with members of the BAR domain protein family of membrane shapers and to unveil the molecular mechanisms Ankrd24 uses for its functions by comprehensive biochemical studies, (ultra-)high-resolution imaging and functional analyses. Detailed characterizations of the molecular mechanistic properties and cell biological functions of Ankrd24 will reveal the fundamental principles Ankrd24 uses to interact with and modulate the topology of membranes. Analyses of Ankrd24 splice variants that affect the N-Ank module will give important insights into the functional consequences of Ankrd24’s alternative splicing in particular and into how to modulate N-Ank module properties in general.Our identification of an interaction of Ankrd24 with another, distinct protein family of membrane shapers furthermore serves as exciting starting point to examine whether and to what extent different membrane topology-recognizing and -modulating proteins cooperate in shaping membranes and entire cells. We will thus address this novel concept by comprehensive biochemical analyses as well as by high-resolution imaging and functional studies in neurons. In summary, studying the mechanisms and the functional role of a putative, novel N-Ank superfamily member in neuromorphogenesis and examining its physical and functional interaction with another membrane shaper of distinct nature will open an important new chapter in our understanding of the morphogenesis of cellular membranes and of entire cells.