Biomaterial Database

Cytoskeletal-membrane interactions: a stable interaction between cell surface glycoconjugates and doublet microtubules of the photoreceptor connecting cilium. 1987

C J Horst, and D M Forestner, and J C Besharse

Department of Anatomy and Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322.

The ciliary base is marked by a transition zone in which Y-shaped cross-linkers extend from doublet microtubules to the plasma membrane. Our goal was to investigate the hypothesis that the cross-linkers form a stable interaction between membrane or cell surface components and the underlying microtubule cytoskeleton. We have combined Triton X-100 extraction with lectin cytochemistry in the photoreceptor sensory cilium to investigate the relationship between cell surface glycoconjugates and the underlying cytoskeleton, and to identify the cell surface components involved. Wheat germ agglutinin (WGA) binds heavily to the cell surface in the region of the Y-shaped cross-linkers of the neonatal rat photoreceptor cilium. WGA binding is not removed by prior digestion with neuraminidase and succinyl-WGA also binds the proximal cilium, suggesting a predominance of N-acetylglucosamine containing glycoconjugates. Extraction of the photoreceptor plasma membrane with Triton X-100 removes the lipid bilayer, leaving the Y-shaped crosslinkers associated with the axoneme. WGA-binding sites are found at the distal ends of the crosslinkers after Triton X-100 extraction, indicating that the microtubule-membrane cross-linkers retain both a transmembrane and a cell surface component after removal of the lipid bilayer. To identify glycoconjugate components of the cross-linkers we used a subcellular fraction enriched in axonemes from adult bovine retinas. Isolated, detergent-extracted bovine axonemes show WGA binding at the distal ends of the cross-linkers similar to that seen in the neonatal rat. Proteins of the axoneme fraction were separated by SDS-PAGE and electrophoretically transferred to nitrocellulose. WGA labeling of the nitrocellulose transblots reveals three glycoconjugates, all of molecular mass greater than 400 kD. The major WGA-binding glycoconjugate has an apparent molecular mass of approximately 600 kD and is insensitive to prior digestion with neuraminidase. This glycoconjugate may correspond to the dominant WGA-binding component seen in cytochemical experiments.

UI	MeSH Term	Description	Entries
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D008870	Microtubules	Slender, cylindrical filaments found in the cytoskeleton of plant and animal cells. They are composed of the protein TUBULIN and are influenced by TUBULIN MODULATORS.	Microtubule
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D010786	Photoreceptor Cells	Specialized cells that detect and transduce light. They are classified into two types based on their light reception structure, the ciliary photoreceptors and the rhabdomeric photoreceptors with MICROVILLI. Ciliary photoreceptor cells use OPSINS that activate a PHOSPHODIESTERASE phosphodiesterase cascade. Rhabdomeric photoreceptor cells use opsins that activate a PHOSPHOLIPASE C cascade.	Ciliary Photoreceptor Cells,Ciliary Photoreceptors,Rhabdomeric Photoreceptor Cells,Rhabdomeric Photoreceptors,Cell, Ciliary Photoreceptor,Cell, Photoreceptor,Cell, Rhabdomeric Photoreceptor,Cells, Ciliary Photoreceptor,Cells, Photoreceptor,Cells, Rhabdomeric Photoreceptor,Ciliary Photoreceptor,Ciliary Photoreceptor Cell,Photoreceptor Cell,Photoreceptor Cell, Ciliary,Photoreceptor Cell, Rhabdomeric,Photoreceptor Cells, Ciliary,Photoreceptor Cells, Rhabdomeric,Photoreceptor, Ciliary,Photoreceptor, Rhabdomeric,Photoreceptors, Ciliary,Photoreceptors, Rhabdomeric,Rhabdomeric Photoreceptor,Rhabdomeric Photoreceptor Cell
D011092	Polyethylene Glycols	Polymers of ETHYLENE OXIDE and water, and their ethers. They vary in consistency from liquid to solid depending on the molecular weight indicated by a number following the name. They are used as SURFACTANTS, dispersing agents, solvents, ointment and suppository bases, vehicles, and tablet excipients. Some specific groups are NONOXYNOLS, OCTOXYNOLS, and POLOXAMERS.	Macrogols,Polyoxyethylenes,Carbowax,Macrogol,Polyethylene Glycol,Polyethylene Oxide,Polyethyleneoxide,Polyglycol,Glycol, Polyethylene,Glycols, Polyethylene,Oxide, Polyethylene,Oxides, Polyethylene,Polyethylene Oxides,Polyethyleneoxides,Polyglycols,Polyoxyethylene
D011506	Proteins	Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.	Gene Products, Protein,Gene Proteins,Protein,Protein Gene Products,Proteins, Gene
D011509	Proteoglycans	Glycoproteins which have a very high polysaccharide content.	Proteoglycan,Proteoglycan Type H
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D002923	Cilia	Populations of thin, motile processes found covering the surface of ciliates (CILIOPHORA) or the free surface of the cells making up ciliated EPITHELIUM. Each cilium arises from a basic granule in the superficial layer of CYTOPLASM. The movement of cilia propels ciliates through the liquid in which they live. The movement of cilia on a ciliated epithelium serves to propel a surface layer of mucus or fluid. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Motile Cilia,Motile Cilium,Nodal Cilia,Nodal Cilium,Primary Cilia,Primary Cilium,Cilium,Cilia, Motile,Cilia, Nodal,Cilia, Primary,Cilium, Motile,Cilium, Nodal,Cilium, Primary
D006001	Glycoconjugates	Carbohydrates covalently linked to a nonsugar moiety (lipids or proteins). The major glycoconjugates are glycoproteins, glycopeptides, peptidoglycans, glycolipids, and lipopolysaccharides. (From Biochemical Nomenclature and Related Documents, 2d ed; From Principles of Biochemistry, 2d ed)	Glycoconjugate