title: Colocalization of pinopsin with two types of G-protein alpha-subunits in the chicken pineal gland.
abstract: Pinopsin is a photoreceptive molecule present in the outer segments of chicken pinealocytes. In this paper, the localization of alpha-subunits of G-proteins, rod transducin (Gt1) and Gq/11, was examined by immunoelectron microscopy to investigate whether these G-proteins colocalize with pinopsin in the outer segments. Ultrathin sections of the chicken pineal gland were double-immunolabeled with antibodies to pinopsin and either Gt1alpha or Gq/11alpha. As shown previously, the outer segments around the follicular lumen exhibited divergent morphology with ciliary, bulbous, or lamellate shapes, and most of them displayed pinopsin immunoreactivity. The majority (>90%) of pinopsin-immunopositive outer segments were labeled by anti-Gt1alpha and/or anti-Gq/11alpha antibodies. Application of double-immunolabeling to serial sections demonstrated that a large number of the pinopsin-immunopositive outer segments contained both Gt1alpha and Gq/11alpha immunoreactivities. These results suggest that Gt1alpha and Gq/11alpha are functionally coupled with light-activated pinopsin within a single outer segment.
authors.affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Matsushita
authors.forename: T
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: T
authors.initials: T
authors.lastname: Okano
authors.forename: T
authors.initials: T
authors.lastname: Kasahara
authors.forename: Y
authors.initials: Y
authors.lastname: Fukada
mesh_terms: D000818:Animals; D030161:Avian Proteins; D002645:Chickens; D002940:Circadian Rhythm; D020962:Heterotrimeric GTP-Binding Proteins / Q000032:analysis*; D016253:Microscopy, Immunoelectron; D009419:Nerve Tissue Proteins / Q000032:analysis*; D010870:Pineal Gland / Q000737:chemistry* / Q000166:cytology / Q000648:ultrastructure; D017299:Rod Opsins / Q000032:analysis*; D015293:Transducin / Q000032:analysis
chemical_list: D030161:Avian Proteins; D020962:Heterotrimeric GTP-Binding Proteins; D009419:Nerve Tissue Proteins; D017299:Rod Opsins; D015293:Transducin; C090139:OPNP protein, chicken