ZFIN ID: ZDB-PUB-050221-8
The Zebrafish pob Gene Encodes a Novel Protein Required for Survival of Red Cone Photoreceptor Cells
Taylor, M.R., Kikkawa, S., Diez-Juan, A., Ramamurthy, V., Kawakami, K., Carmeliet, P., and Brockerhoff, S.E.
Date: 2005
Source: Genetics   170(1): 263-273 (Journal)
Registered Authors: Brockerhoff, Susan, Kawakami, Koichi, Taylor, Michael
Keywords: Zebrafish; partial optokinetic response b (pob); positional cloning; Tol2 transposon
MeSH Terms:
  • Amino Acid Sequence
  • Animals
  • COS Cells
  • Cell Survival/genetics
  • Chlorocebus aethiops
  • Humans
  • Immunohistochemistry
  • In Situ Hybridization
  • Membrane Proteins/genetics*
  • Membrane Proteins/physiology
  • Mice
  • Molecular Sequence Data
  • Retinal Cone Photoreceptor Cells/metabolism*
  • Zebrafish/genetics*
  • Zebrafish/metabolism
  • Zebrafish Proteins/genetics*
  • Zebrafish Proteins/physiology
PubMed: 15716502 Full text @ Genetics
The zebrafish mutant, partial optokinetic response b (pob), was isolated using an n-ethyl n-nitrosourea (ENU)-based screening strategy designed to identify larvae with defective optokinetic responses in red but not white light. Previous studies showed that red-light blindness in pob is due to the specific loss of long-wavelength photoreceptor cells via an apoptotic mechanism. Here, we used positional cloning to identify the mutated pob gene. We find that pob encodes a highly conserved 30kDa protein of unknown function. To demonstrate that the correct gene was isolated, we used the Tol2 transposon system to generate transgenic animals and rescue the mutant phenotype. The Pob protein contains putative transmembrane regions and protein sorting signals. It is localized to the inner segment and synapse in photoreceptor cells, and when expressed in COS-7 cells it localizes to intracellular compartments. We also show that the degeneration of red cone photoreceptors in the mutants occurs independently of light. Based on our findings, we propose that Pob is not involved in phototransduction but rather plays an essential role in protein sorting and/or trafficking.