Functional expression and characterization of frog photoreceptor-specific calcium-binding proteins.
S-modulin (sensitivity-modulating protein) is a photoreceptor-specific calcium-binding protein which plays an important role in the light adaptation process by controlling rhodopsin phosphorylation in rods. S-modulin and its cone homologue, s26, were expressed at high level (more than 30% of total protein) in Escherichia coli and then purified. They both inhibited rhodopsin phosphorylation in a calcium dependent manner. Myristoylated recombinants of S-modulin and s26 showed calcium-dependent changes in tryptophan emission spectra with half-maxima at about 0.7 microM free calcium concentration. However, the spectral changes are distinctive from each other, suggesting that there is some difference in the structural change between S-modulin and s26.
Hisatomi
O
O
Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Japan.
Ishino
T
T
Matsuda
S
S
Yamaguchi
K
K
Kobayashi
Y
Y
Kawamura
S
S
Tokunaga
F
F
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001001:Anura; D002118:Calcium / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D002942:Circular Dichroism; D003001:Cloning, Molecular; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D005136:Eye Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D015870:Gene Expression / Q000235:genetics; D051597:Hippocalcin; D008074:Lipoproteins; D009226:Myristates / Q000378:metabolism; D009419:Nerve Tissue Proteins; D010766:Phosphorylation; D010786:Photoreceptor Cells / Q000737:chemistry; D010957:Plasmids; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D051603:Recoverin; D012243:Rhodopsin / Q000378:metabolism; D013050:Spectrometry, Fluorescence
D002135:Calcium-Binding Proteins; D017931:DNA Primers; D005136:Eye Proteins; D008074:Lipoproteins; D009226:Myristates; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; C101179:photoreceptor protein s26, Rana catesbeiana; D051603:Recoverin; D051597:Hippocalcin; D000255:Adenosine Triphosphate; D012243:Rhodopsin; D002118:Calcium