Search results for "Ciliary membrane"
showing 5 items of 5 documents
Protein Networks and Complexes in Photoreceptor Cilia
2007
Vertebrate photoreceptor cells are ciliated sensory cells specialized for single photon detection. The photoreceptor outer segment corresponds to the ciliary shaft of a prototypic cilium. In the outer segment compartment, the ciliary membrane is highly modified into membranous disks which are enveloped by the plasma membrane in rod cells. At these outer segment disks, the visual transduction cascade--a prototypical G-protein coupled receptor transduction pathway is arranged. The light sensitive outer segments are linked by the socalled connecting cilium with the inner segment, the photoreceptor compartment which contains all organelles necessary for cell metabolism. The connecting cilium co…
Evidence for Myosin VIIa-Driven Transport of Rhodopsin in the Plasma Membrane of the Photoreceptor-Connecting Cilium
2007
Defects in the gene encoding for the unconventional myosin VIIa leads to human Usher syndrome 1B, the most common form of hereditary combined blindness and deafness. To determine cellular function of myosin VIIa, we have investigated the subcellular localization of myosin VIIa in spacial relation relationship to potentially interacting proteins in mammalian photoreceptor cells. Western blot analysis of the axonemal fraction of photoreceptor cells by Western blot show that myosin VIIa and actin, as well as opsin, were present in the ciliary portion of the photoreceptors. Improved immunoelectron microscopy revealed that in mammalian photoreceptor cells, myosin VIIa was localized at the membra…
Rhodopsin transport in the membrane of the connecting cilium of mammalian photoreceptor cells
2000
The transport of the photopigment rhodopsin from the inner segment to the photosensitive outer segment of vertebrate photoreceptor cells has been one of the main remaining mysteries in photoreceptor cell biology. Because of the lack of any direct evidence for the pathway through the photoreceptor cilium, alternative extracellular pathways have been proposed. Our primary aim in the present study was to resolve rhodopsin trafficking from the inner to the outer segment. We demonstrate, predominantly by high-sensitive immunoelectron microscopy, that rhodopsin is also densely packed in the membrane of the photoreceptor connecting cilium. Present prominent labeling of rhodopsin in the ciliary mem…
A Transition Zone Complex Regulates Mammalian Ciliogenesis and Ciliary Membrane Composition
2011
Mutations in genes encoding ciliary components cause ciliopathies, but how many of these mutations disrupt ciliary function is unclear. We investigated Tectonic1 (Tctn1), a regulator of mouse Hedgehog signaling, and found that it is essential for ciliogenesis in some, but not all, tissues. Cell types that do not require Tctn1 for ciliogenesis require it to localize select membrane-associated proteins to the cilium, including Arl13b, AC3, Smoothened and Pkd2. Tctn1 forms a complex with multiple ciliopathy proteins associated with Meckel (MKS) and Joubert (JBTS) syndromes, including Mks1, Tmem216, Tmem67, Cep290, B9d1, Tctn2, and Cc2d2a. Components of the Tectonic ciliopathy complex colocaliz…
PCARE and WASF3 regulate ciliary F-actin assembly that is required for the initiation of photoreceptor outer segment disk formation
2020
Significance The photoreceptor outer segments are primary cilia, modified for phototransduction by incorporation of stacked opsin-loaded membrane disks that are continuously regenerated. This process is disrupted in several types of inherited retinal dystrophy, but the driving force remained unclear. We show that C2orf71/PCARE (photoreceptor cilium actin regulator), associated with inherited retinal dystrophy subtype RP54, efficiently recruits the Arp2/3 complex activator WASF3 to the cilium. This activates an actin dynamics-driven expansion of the ciliary tip, resembling membrane evagination in lamellipodia formation. Colocalization of this actin dynamics module to the base of the outer se…