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Protein Pages
Maintaining the Structural Integrity of Retinal Cells and Tissues

Recent update from: 09.08.1999

Disc close up
Disc Overview This pages deals with the proteins involved in the maintenance of the cell shape (e.g. the photoreceptor outer segments) and the retinal tissues.
To built up the organised structure of a tissue, growth factors regulate the development and interaction of the cells involved. To establish the shape of a cell, structural proteins like microtubuli, actin and other structural proteins are involved.

Two specialised proteins establish the shape of photoreceptor outer segments RDS/Peripherin and ROM1. They are localised along the rims of the discs and connected with microtubules running along the length of a photoreceptor outer segment (2). RDS/Peripherin and ROM1 form homodimers which are combined to hetero-octamers by disulphide bonds to establish the disc shape (1).

Of further importance for the maintenance of the retinal tissue are metalloproteases and their inhibitors. Metalloproteases are proteins which destroy or (better) digest proteins. During the night the photoreceptor outer segments shed about 1000 discs from their tips which then are ingested by the RPE and digested in the RPE lysosomes.
On remodelling a tissue these functions are established by the tissue cells itself.
To establish a controlled digestion of a tissue Tissue Inhibitors of Metalloproteases (TIMP) are active. One of these Tissue Inhibitors of Metalloproteases TIMP3 is known to be involved in Sorsby's Fundus Dystrophy (SFD) (3).

Photoreceptor Outer Segment

  1. Molday,L.L. and Molday,R.S. Structural And Enzymatic Properties Of The ABCR Protein Of Rod Photoreceptors. 1998; Invest.Ophthalmol.Vis.Sci. 39: S963
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  2. Molday,R.S. Photoreceptor membrane proteins, phototransduction, and retinal degenerative diseases. The Friedenwald Lecture. 1998; Invest.Ophthalmol.Vis.Sci. 39: 2491-2513.
    Link to PubMed
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  3. Weber,B.H., Vogt,G., Pruett,R.C., Stohr,H., and Felbor,U. Mutations in the tissue inhibitor of metalloproteinases-3 (TIMP3) in patients with Sorsby's fundus dystrophy. 1994; Nat.Genet. 8: 352-356.
    Link to PubMed
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This site is maintained and edited by
Dr. rer. medic. Markus Preising, Dipl.Biol.
Molecular Genetics Laboratory
Department of Paediatric Ophthalmology, Strabismology and Ophthalmogenetics
University of Regensburg
Head: Prof. Dr. med. Birgit Lorenz