title: Neurocalcin delta modulation of ROS-GC1, a new model of Ca(2+) signaling.
abstract: ROS-GC1 membrane guanylate cyclase is a Ca(2+) bimodal signal transduction switch. It is turned "off" by a rise in free Ca(2+) from nanomolar to the semicromolar range in the photoreceptor outer segments and the olfactory bulb neurons; by a similar rise in the bipolar and ganglion retinal neurons it is turned "on". These opposite operational modes of the switch are specified by its Ca(2+) sensing devices, respectively termed GCAPs and CD-GCAPs. Neurocalcin delta is a CD-GCAP. In the present study, the neurocalcin delta-modulated site, V(837)-L(858), in ROS-GC1 has been mapped. The location and properties of this site are unique. It resides within the core domain of the catalytic module and does not require the alpha-helical dimerization domain structural element (amino acids 767-811) for activating the catalytic module. Contrary to the current beliefs, the catalytic module is intrinsically active; it is directly regulated by the neurocalcin delta-modulated Ca(2+) signal and is dimeric in nature. A fold recognition based model of the catalytic domain of ROS-GC1 was built, and neurocalcin delta docking simulations were carried out to define the three-dimensional features of the interacting domains of the two molecules. These findings define a new transduction model for the Ca(2+) signaling of ROS-GC1.
authors.affiliation: Department of Cell Biology, UMDNJ-SOM, Stratford, New Jersey 08084, USA.
authors.forename: Venkateswar
authors.initials: V
authors.lastname: Venkataraman
authors.forename: Teresa
authors.initials: T
authors.lastname: Duda
authors.forename: Sarangan
authors.initials: S
authors.lastname: Ravichandran
authors.forename: Rameshwar K
authors.initials: RK
authors.lastname: Sharma
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D020134:Catalytic Domain; D002522:Chlorocebus aethiops; D006162:Guanylate Cyclase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D051596:Neurocalcin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020349:Surface Plasmon Resonance; D014162:Transfection
chemical_list: D051596:Neurocalcin; D011956:Receptors, Cell Surface; C110715:guanylate cyclase 1; D006162:Guanylate Cyclase; D002118:Calcium