Parietal-Eye Phototransduction Components and Their Potential Evolutionary Implications

  title={Parietal-Eye Phototransduction Components and Their Potential Evolutionary Implications},
  author={C Y Su and Dong Gen Luo and Akihisa Terakita and Yoshinori Shichida and Hsi Wen Liao and Manija A. Kazmi and Thomas P. Sakmar and King-Wai Yau},
  pages={1617 - 1621}
The parietal-eye photoreceptor is unique because it has two antagonistic light signaling pathways in the same cell—a hyperpolarizing pathway maximally sensitive to blue light and a depolarizing pathway maximally sensitive to green light. Here, we report the molecular components of these two pathways. We found two opsins in the same cell: the blue-sensitive pinopsin and a previously unidentified green-sensitive opsin, which we name parietopsin. Signaling components included gustducin-α and Gαo… 

Phototransduction in ganglion-cell photoreceptors

  • D. Berson
  • Biology
    Pflügers Archiv - European Journal of Physiology
  • 2007
The overwhelming evidence that melanopsin serves as the photopigment in these cells is summarized and the emerging evidence that the downstream signaling cascade, including the light-gated channel, might resemble those found in rhabdomeric invertebrate photoreceptors is reviewed.

Vertebrate Bistable Pigment Parapinopsin: Implications for Emergence of Visual Signaling and Neofunctionalization of Non-visual Pigment

A plausible link between the diversification of a non-visual opsin parapinopsin and diverse pineal functions, wavelength discrimination, and melatonin secretion, implying why multiple opsins exist in animals, is proposed.

Vision: Under the spotlight

  • J. Qiu
  • Biology
    Nature Reviews Neuroscience
  • 2006
The molecular machinery that underlies these pathways of light detection in the parietal eye is revealed, and it is suggested that the third eye is more primitive, and that imageforming lateral eyes might have evolved from their parietal ancestor but inherited only one G-protein pathway.

Jellyfish vision starts with cAMP signaling mediated by opsin-Gs cascade

It is shown that the opsin-based pigment functions as a green-sensitive visual pigment and triggers the Gs-type G protein-mediated phototransduction cascade in the ciliary-type visual cells of the box jellyfish lens eyes, which implies a monophyletic origin of ciliary phototranduction cascades distributed from prebilaterian to vertebrate.

Evolution of opsins and phototransduction

This work discusses the evolution of the counterion, the reduction of agonist binding to the receptor, and the molecular properties that characterize rod opsins apart from cone opsins, and shows how the advances in molecular biology and biophysics have given insights into how evolution works at the molecular level.

Phototransduction Motifs and Variations

Molecular and functional identification of a novel photopigment in Pecten ciliary photoreceptors

Results establish this novel putative opsin as a bona fide visual pigment that couples to Go to convey the light signal.

Molecular Aspects of Evolution and Diversity of Animal Photoreception

The visual transduction process in vertebrate and invertebrate photoreceptor cells, and the functional diversity of opsins and phototransduction systems in various photorecept cells are reviewed; the molecular mechanisms underlying the evolution and diversity of Opsins are discussed.

Photochemical nature of parietopsin.

The mutational analysis revealed that parietopsin behaves as an "evolutionary intermediate" between invertebrate and vertebrate visual opsins.



A Novel Go-mediated Phototransduction Cascade in Scallop Visual Cells*

The phototransduction cascade in the scallop hyperpolarizing cell provides an alternative system to investigate Go-mediated transduction pathways in the nervous system and Molecular phylogenetic analysis strongly suggests that the Go- mediated phototranduction system emerged before the divergence of animals into vertebrate and invertebrate in the course of evolution.

A cGMP-gated cation channel in depolarizing photoreceptors of the lizard parietal eye

Surprisingly, in excised membrane patches a cGMP-gated channel is found that is selectively present at high density on the outer segment of the parietal eye photoreceptor, and like the light-activated channel of the cell, it is non-selective among cations.

Light Transduction in Invertebrate Hyperpolarizing Photoreceptors: Possible Involvement of a Go-Regulated Guanylate Cyclase

A novel type of phototransduction cascade is suggested in which stimulation of a PTX-sensitive Go may activate a membrane GC to induce an increase in cGMP and the consequent opening of light-dependent channels.

Ciliary Photoreceptors with a Vertebrate-Type Opsin in an Invertebrate Brain

Comparative analysis indicates that both types of photoreceptors, with distinct opsins, coexisted in Urbilateria, the last common ancestor of insects and vertebrates, and sheds new light on vertebrate eye evolution.

Antagonistic chromatic mechanisms in photoreceptors of the parietal eye of lizards

It is reported here that chromatic antagonism in the third eye originates in the chromatically dependent hyperpolarizing and depolarizing response of the photoreceptors to light and suggested that the antagonistic nature of these photoresponses may provide lizards with a mechanism for the enhanced detection of dawn and dusk.

Pinopsin is a chicken pineal photoreceptive molecule

Cloned chicken pineal cDNA encoding the photoreceptive molecule is cloned and it is confirmed that it is a pineal photosensor and named pinopsin, indicating a similarity between retinal rod cells and pinealocytes in the phototransduction pathway.

Rod‐Type Transducin α‐Subunit Mediates a Phototransduction Pathway in the Chicken Pineal Gland

The cDNA cloning of the pineal transducin α‐subunit (Gtα) is reported, which is highly homologous to human retinal rod cell‐specific Gt1α, which suggests strongly that pineal Gt 1α mediates the phototransduction pathway triggered by pinopsin in the chicken pinealocytes.

Pineal opsin: a nonvisual opsin expressed in chick pineal

The primary sequence of P-opsin suggests that it will be maximally sensitive to approximately 500-nanometer light and produce a slow and prolonged phototransduction response consistent with the nonvisual function of pineal photoreception.

Parapinopsin, a Novel Catfish Opsin Localized to the Parapineal Organ, Defines a New Gene Family

No expression of retinal opsins in pineal and parapineal organ and no expression of any opsin tested in the “deep brain,” iris, or dermal melanophores imply that phototransduction in these sites of extraretinal photoreception must be mediated by novel opsins.