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Entry
map04744                    Pathway                                

Name
Phototransduction
Description
Phototransduction is a biochemical process by which the photoreceptor cells generate electrical signals in response to captured photons. The vertebrate cascade starts with the absorption of photons by the photoreceptive pigments, the rhodopsins, which consist of a membrane embedded chromophore, 11-cis-retinal, and a G-protein-coupled receptor, opsin. The photon isomerizes 11-cis-retinal to all-trans-retinal which induces a structural change that activates the opsin. This triggers hydrolysis of cGMP by activating a transducinphosphodiesterase 6 (PDE6) cascade, which results in closure of the cGMP-gated cation channels (CNG) in the plasma membrane and membrane hyperpolarization. The hyperpolarization of the membrane potential of the photoreceptor cell modulates the release of neurotransmitters to downstream cells. Recovery from light involves the deactivation of the light- activated intermediates: photolyzed rhodopsin is phosphorylated by rhodopsin kinase (RK) and subsequently capped off by arrestin; GTP-binding transducin alpha subunit deactivates through a process that is stimulated by RGS9.
Class
Organismal Systems; Sensory system
BRITE hierarchy
Pathway map
Phototransduction
map04744

All organismsOrtholog table
Disease
H00481  
Cone-rod dystrophy and cone dystrophy
H00527  
Retinitis pigmentosa (RP)
H00787  
Congenital stationary night blindness (CSNB)
H00825  
Familial flecked retina syndrome
H00837  
Leber congenital amaurosis (LCR)
H00973  
Bradyopsia
Other DBs
GO: 
Reference
  Authors
Yau KW, Hardie RC
  Title
Phototransduction motifs and variations.
  Journal
Cell 139:246-64 (2009)
Reference
  Authors
Koch KW, Duda T, Sharma RK
  Title
Photoreceptor specific guanylate cyclases in vertebrate phototransduction.
  Journal
Mol Cell Biochem 230:97-106 (2002)
Reference
PMID:9803480
  Authors
Jindrova H
  Title
Vertebrate phototransduction: activation, recovery, and adaptation.
  Journal
Physiol Res 47:155-68 (1998)
Reference
  Authors
Ebrey T, Koutalos Y
  Title
Vertebrate photoreceptors.
  Journal
Prog Retin Eye Res 20:49-94 (2001)
Reference
  Authors
Pepe IM
  Title
Recent advances in our understanding of rhodopsin and phototransduction.
  Journal
Prog Retin Eye Res 20:733-59 (2001)
Reference
  Authors
Kramer RH, Molokanova E
  Title
Modulation of cyclic-nucleotide-gated channels and regulation of vertebrate phototransduction.
  Journal
J Exp Biol 204:2921-31 (2001)
Reference
  Authors
Larhammar D, Nordstrom K, Larsson TA
  Title
Evolution of vertebrate rod and cone phototransduction genes.
  Journal
Philos Trans R Soc Lond B Biol Sci 364:2867-80 (2009)
Reference
  Authors
Dizhoor AM, Olshevskaya EV, Peshenko IV
  Title
Mg2+/Ca2+ cation binding cycle of guanylyl cyclase activating proteins (GCAPs): role in regulation of photoreceptor guanylyl cyclase.
  Journal
Mol Cell Biochem 334:117-24 (2010)
Reference
  Authors
Krizaj D, Copenhagen DR
  Title
Calcium regulation in photoreceptors.
  Journal
Front Biosci 7:d2023-44 (2002)
Reference
PMID:9893707
  Authors
Shichida Y, Imai H
  Title
Visual pigment: G-protein-coupled receptor for light signals.
  Journal
Cell Mol Life Sci 54:1299-315 (1998)
Reference
PMID:9419388
  Authors
Pugh EN Jr, Duda T, Sitaramayya A, Sharma RK
  Title
Photoreceptor guanylate cyclases: a review.
  Journal
Biosci Rep 17:429-73 (1997)
Reference
  Authors
Luo DG, Xue T, Yau KW
  Title
How vision begins: an odyssey.
  Journal
Proc Natl Acad Sci U S A 105:9855-62 (2008)
Reference
  Authors
Peshenko IV, Dizhoor AM
  Title
Activation and inhibition of photoreceptor guanylyl cyclase by guanylyl cyclase activating protein 1 (GCAP-1): the functional role of Mg2+/Ca2+ exchange in EF-hand domains.
  Journal
J Biol Chem 282:21645-52 (2007)
Reference
  Authors
Ridge KD, Abdulaev NG, Sousa M, Palczewski K
  Title
Phototransduction: crystal clear.
  Journal
Trends Biochem Sci 28:479-87 (2003)
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