Immunocytochemical identification of pinopsin in pineal glands of chicken and pigeon

Toshiyuki Okano, Yoko Takanaka, Atsushi Nakamura, Kanjun Hirunagi, Akihito Adachi, Shizufumi Ebihara, Yoshitaka Fukada*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

59 Citations (Scopus)


Pinopsin is a blue-sensitive photoreceptive molecule possibly involved in photic entrainment of the circadian pacemaker in the chicken pineal gland. To characterize pinopsin as a circadian photoreceptor, antibodies were raised against the C-terminal portion of pinopsin. As expected from the divergence of the amino acid sequence of this region, the resultant antibody cross-reacted with neither chicken rhodopsin nor red-sensitive cone pigment (chicken red). In Western blot analysis, the antibody stained a single band of 42-kDa protein in a detergent-extract of chicken pineal membranes, suggesting that pinopsin (calculated molecular weight, 38187) might be glycosylated and/or palmitoylated. Immunocytochemical examination of pineal sections of the chicken and the pigeon with this antibody revealed strong positive images for most of the membrane structures in the lumen of the follicles. This antibody also stained string- and bulb-shaped structures of the chicken parafollicular cells, the morphology of which resembles those of retinal photoreceptor cells. In contrast to the predominant distribution of pinopsin, a monoclonal antibody specific for chicken red stained a smaller number of membrane structures in the lumen of chicken pineal follicles. These results strongly suggest that the chicken pineal gland contains at least two types of photoreceptive molecules, pinopsin (major) and chicken red (minor). We show that the former molecule is localized in parafollicular pinealocytes and in the outer segments of pinealocytes that make contact with the follicular lumen.

Original languageEnglish
Pages (from-to)190-196
Number of pages7
JournalMolecular Brain Research
Issue number1-2
Publication statusPublished - 1997 Oct 15
Externally publishedYes


  • Chicken
  • Chicken red
  • Circadian clock
  • Immunocytochemistry
  • Pineal gland
  • Pinopsin

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience


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