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Mol Biol Cell 2003 Aug 01;148:3400-13. doi: 10.1091/mbc.e03-02-0077.
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The role of subunit assembly in peripherin-2 targeting to rod photoreceptor disk membranes and retinitis pigmentosa.

Loewen CJ , Moritz OL , Tam BM , Papermaster DS , Molday RS .

Peripherin-2 is a member of the tetraspanin family of membrane proteins that plays a critical role in photoreceptor outer segment disk morphogenesis. Mutations in peripherin-2 are responsible for various retinal degenerative diseases including autosomal dominant retinitis pigmentosa (ADRP). To identify determinants required for peripherin-2 targeting to disk membranes and elucidate mechanisms underlying ADRP, we have generated transgenic Xenopus tadpoles expressing wild-type and ADRP-linked peripherin-2 mutants as green fluorescent fusion proteins in rod photoreceptors. Wild-type peripherin-2 and P216L and C150S mutants, which assemble as tetramers, targeted to disk membranes as visualized by confocal and electron microscopy. In contrast the C214S and L185P mutants, which form homodimers, but not tetramers, were retained in the rod inner segment. Only the P216L disease mutant induced photoreceptor degeneration. These results indicate that tetramerization is required for peripherin-2 targeting and incorporation into disk membranes. Tetramerization-defective mutants cause ADRP through a deficiency in wild-type peripherin-2, whereas tetramerization-competent P216L peripherin-2 causes ADRP through a dominant negative effect, possibly arising from the introduction of a new oligosaccharide chain that destabilizes disks. Our results further indicate that a checkpoint between the photoreceptor inner and outer segments allows only correctly assembled peripherin-2 tetramers to be incorporated into nascent disk membranes.

PubMed ID: 12925772
PMC ID: PMC181576
Article link: Mol Biol Cell
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: canx dnai1 plin2 prph prph2 rasl12 rpe tbx2
Antibodies: Prph2 Ab1 Wheat Germ Agglutinin

Article Images: [+] show captions
References [+] :
Arikawa, Localization of peripherin/rds in the disk membranes of cone and rod photoreceptors: relationship to disk membrane morphogenesis and retinal degeneration. 1992, Pubmed