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J Cell Biol November 3, 2008; 183 (3): 485-98.

The outer segment serves as a default destination for the trafficking of membrane proteins in photoreceptors.

Baker SA , Haeri M , Yoo P , Gospe SM , Skiba NP , Knox BE , Arshavsky VY .

Photoreceptors are compartmentalized neurons in which all proteins responsible for evoking visual signals are confined to the outer segment. Yet, the mechanisms responsible for establishing and maintaining photoreceptor compartmentalization are poorly understood. Here we investigated the targeting of two related membrane proteins, R9AP and syntaxin 3, one residing within and the other excluded from the outer segment. Surprisingly, we have found that only syntaxin 3 has targeting information encoded in its sequence and its removal redirects this protein to the outer segment. Furthermore, proteins residing in the endoplasmic reticulum and mitochondria were similarly redirected to the outer segment after removing their targeting signals. This reveals a pattern where membrane proteins lacking specific targeting information are delivered to the outer segment, which is likely to reflect the enormous appetite of this organelle for new material necessitated by its constant renewal. This also implies that every protein residing outside the outer segment must have a means to avoid this "default" trafficking flow.

PubMed ID: 18981232
PMC ID: PMC2575789
Article link: J Cell Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: actl6a grm1 myc nos1 nos3 rgs9 rgs9bp rpe stx3 tbx2 zic1
Antibodies: Stx3 Ab1

Article Images: [+] show captions
References [+] :
Amaya, A method for generating transgenic frog embryos. 1999, Pubmed, Xenbase