Pinwheel-like structure

Clathrin is a major coat protein of coated pits and coated vesicles formed in receptor-mediated endocytosis and intracellular vesicle-mediated transport and has a unique pinwheel-like structure in solution termed a triskelion composed of three heavy chains and three light chains [9]. Previously, we found that below pH 6, clathrin forms self-aggregates in the absence of liposomes and fusogenic assemblies in their presence [10, 11]. 

Figure 2. The equilibrium structure of (HCCH)i3 calculated [167] with a polarizable model potential. The central molecule is seen essentially end on. The 12 surrounding molecules are in three layers. The upper and lower layers have three molecules and resemble the structure of the cyclic trimer of acetylene. The middle layer of six acetylene molecules has a pinwheel like arrangement. Puckering of the rings in the layers yields T shaped orientations between acetylenes in different layers, along with the essentially T shaped arrangements for adjacent molecules within each layer. The number of favorable (T shaped) quadrupole quadrupole interactions among acetylenes is thereby enhanced.

The zeolites discussed so far have all relied on exotic organocations to function as SDAs. However, sometimes the inorganic cations can have a greater influence as demonstrated by the 12-MR zincosilicate, VPI-8 (65-68). The synthesis of VPI-8 still requires an organic additive but its role as template may be as a void filler. A recently determined model for the structure of VPI-8 viewed along the 001 direction is shown in Fig. 10 (69). Much like SSZ-31, the structure of VPI-8 involves ID channels running in parallel that are defined by odd-shaped 12-MR structures (6.2 x 5.97 x 5.88 A). An unusual feature of this structure is the pinwheel building unit that is composed of four 5-MR stmctures surrounded by another four 5-MR structures. 

---