Ca2+-myristoyl switch in the neuronal calcium sensor recoverin requires different functions of Ca2+-binding sites.
Recoverin is an EF-hand Ca(2+)-binding protein that is suggested to control the activity of the G-protein-coupled receptor kinase GRK-1 or rhodopsin kinase in a Ca(2+)-dependent manner. It undergoes a Ca(2+)-myristoyl switch when Ca(2+) binds to EF-hand 2 and 3. We investigated the mechanism of this switch by the use of point mutations in EF-hand 2 (E85Q) and 3 (E121Q) that impair their Ca(2+) binding. EF-hand 2 and 3 display different properties and serve different functions. Binding of Ca(2+) to recoverin is a sequential process, wherein EF-hand 3 is occupied first followed by the filling of EF-hand 2. After EF-hand 3 bound Ca(2+), the subsequent filling of EF-hand 2 triggers the exposition of the myristoyl group and in turn binding of recoverin to membranes. In addition, EF-hand 2 controls the mean residence time of recoverin at membranes by decreasing the dissociation rate of recoverin from membranes by 10-fold. We discuss this mechanism as one critical step for inhibition of rhodopsin kinase by recoverin.
Senin
Ivan I
II
A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia.
Fischer
Torsten
T
Komolov
Konstantin E
KE
Zinchenko
Dimitry V
DV
Philippov
Pavel P
PP
Koch
Karl-Wilhelm
KW
D000818:Animals; D001665:Binding Sites; D014408:Biomarkers, Tumor / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D003001:Cloning, Molecular; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005136:Eye Proteins; D051606:G-Protein-Coupled Receptor Kinase 1; D051597:Hippocalcin; D007700:Kinetics; D008074:Lipoproteins; D008081:Liposomes; D016297:Mutagenesis, Site-Directed; D019814:Myristic Acid / Q000378:metabolism*; D009419:Nerve Tissue Proteins; D011494:Protein Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D051603:Recoverin; D012374:Rod Cell Outer Segment / Q000378:metabolism*
D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins; D005136:Eye Proteins; D008074:Lipoproteins; D008081:Liposomes; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; D019814:Myristic Acid; D051603:Recoverin; D051597:Hippocalcin; D011494:Protein Kinases; D051606:G-Protein-Coupled Receptor Kinase 1; D002118:Calcium