Centrins, gatekeepers for the light-dependent translocation of transducin through the photoreceptor cell connecting cilium.
Centrins are members of a highly conserved subgroup of the EF-hand superfamily of Ca(2+)-binding proteins commonly associated with centrosome-related structures. In the retina, centrins are also prominent components of the photoreceptor cell ciliary apparatus. Centrin isoforms are differentially localized at the basal body and in the lumen of the connecting cilium. All molecular exchanges between the inner and outer segments occur through this narrow connecting cilium. Ca(2+)-activated centrin isoforms bind to the visual heterotrimeric G-protein transducin via an interaction with the betagamma-subunit. Ca(2+)-dependent assemblies of centrin/G-protein complexes may regulate the transducin movement through the connecting cilium. Formation of this complex represents a novel mechanism in regulation of translocation of signaling proteins in sensory cells, as well as a potential link between molecular trafficking and signal transduction in general.
Giessl
Andreas
A
Johannes Gutenberg-University, Institute of Zoology, Department of Cell and Matrix Biology, Mainz, Germany.
Trojan
Philipp
P
Rausch
Sebastian
S
Pulvermüller
Alexander
A
Wolfrum
Uwe
U
D000818:Animals; D002135:Calcium-Binding Proteins / Q000502:physiology*; D018385:Centrosome / Q000378:metabolism; D002923:Cilia / Q000378:metabolism*; D010766:Phosphorylation; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000378:metabolism*; D021381:Protein Transport; D015293:Transducin / Q000378:metabolism*; D014714:Vertebrates / Q000378:metabolism*; D014785:Vision, Ocular / Q000502:physiology
D002135:Calcium-Binding Proteins; D015293:Transducin