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. Author manuscript; available in PMC: 2010 Oct 13.
Published in final edited form as: Neurobiol Dis. 2010 Jan 22;38(2):167–172. doi: 10.1016/j.nbd.2009.12.022

Fig. 1.

Fig. 1

Schematic diagram of primary cilium. Primary cilia lack the central microtubule pair and their cross-section show ‘9+0’ arrangement (inset). Cilia structure and function are maintained by intraflagellar transport (IFT) within primary cilia. The protein cargo is produced in the Golgi apparatus, moves towards the cilium, and binds to the IFT complex. IFT complex/cargo assembly can be transported along microtubules. The anterograde movement (toward the tip of the cilium) of IFT complex/cargo assembly relies on kinesin 2, while dynein 2 transports in the retrograde direction (toward the basal body of the cilium). Functionally, primary cilia are involved in various signaling pathways including Sonic hedgehog (Shh), Wnt, platelet-derived growth factor (PDGF), and G-protein coupled receptor (GPCR). These signaling pathways play important roles in regulating various neuronal functions including cerebellar development, hippocampal neurogenesis, and obesity. Abbreviations: PTCH, Patched 1; PDGFR, Platelet-derived growth factor receptor.