Centrins, a novel group of Ca2+-binding proteins in vertebrate photoreceptor cells.
Changes in the intracellular Ca2+-concentration affect the visual signal transduction cascade directly or more often indirectly through Ca2+-binding proteins. Here we review recent findings on centrins in photoreceptor cells of the mammalian retina. Centrins are members of a highly conserved subgroup of the EF-hand superfamily of Ca2+-binding proteins commonly associated with centrosome-related structures. In vertebrate photoreceptor cells, centrins are also prominent components in the connecting cilium linking the light sensitive outer segment with the biosynthetically active inner segment compartment. Recent findings demonstrate that Ca2+-activated centrin forms a complex with the visual G-protein transducin in photoreceptor cells. This Ca2+-dependent assembly of G-proteins with centrin is a novel aspect of the supply of signaling proteins in sensory cells, and a potential link between molecular translocations and signal transduction in general.
Wolfrum
Uwe
U
Institut für Zoologie, Johannes Gutenberg-Universitit Mainz, 55099 Mainz, Germany. wolfrum@mail.uni-mainz.de
Giessl
Andreas
A
Pulvermüller
Alexander
A
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone; D003599:Cytoskeleton; D019204:GTP-Binding Proteins; D008954:Models, Biological; D008969:Molecular Sequence Data; D010786:Photoreceptor Cells / Q000166:cytology / Q000378:metabolism*; D010802:Phylogeny; D020033:Protein Isoforms; D021381:Protein Transport; D017386:Sequence Homology, Amino Acid; D014714:Vertebrates / Q000378:metabolism
D002135:Calcium-Binding Proteins; D002868:Chromosomal Proteins, Non-Histone; D020033:Protein Isoforms; C056608:caltractin; D019204:GTP-Binding Proteins