Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P05231 (interleukin-6)
 23,907 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

S-modulin is a 26 kDa protein that regulates light sensitivity of cGMP phosphodiesterase in a Ca(2+)-dependent manner in frog rod outer segments (ROSs). In the present study, we purified S-modulin by taking advantage of a hydrophobic interaction between Phenyl Sepharose and S-modulin at high Ca2+ concentrations. The yield was greater than 90%. 45Ca(2+)-binding experiment showed that S-modulin is a Ca(2+)-binding protein. At high Ca2+ concentrations, S-modulin binds to ROS membranes. The binding target of the Ca2+/S-modulin complex is possibly a ROS membrane lipid(s), but it was difficult to identify. The binding was observed mainly at greater than 1 microM Ca2+. The amino acid sequence deduced from proteolytic fragments of S-modulin was approximately 80% and 60% identical to those of recovering and visinin, respectively.
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PMID:Purification and characterization of S-modulin, a calcium-dependent regulator on cGMP phosphodiesterase in frog rod photoreceptors. 132 10

Cyclic GMP is the second messenger in the phototransduction mechanism in rod photoreceptors. Light-induced activation of cGMP phosphodiesterase (PDE), the hydrolyzing enzyme of cGMP, reduces cytoplasmic cGMP concentration to close the cGMP-activated channel and thereby causes a hyperpolarizing light response. Ca2+ concentration decreases during light-adaptation and this decrease is thought to be at least one of the underlying mechanisms of light-adaptation. Our previous electrophysiological work suggested that PDE in frog rod photoreceptors is regulated by this Ca2+ concentration decrease. In the present work, we isolated a protein that binds to disk membranes at high Ca2+ concentrations. In the presence of this protein (a 26 kDa protein), PDE light sensitivity becomes high at high Ca2+ concentrations. The effect was observed at physiological ranges of Ca2+ concentrations. Thus we could explain high light-sensitivity of photoreceptors under the dark-adapted condition. According to its function, we termed the 26 kDa protein 'sensitivity-modulating protein' or 'S-modulin'. During the purification we noticed that there are additional mechanisms present that may contribute to light-adaptation in frog rod photoreceptors.
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PMID:Light-sensitivity modulating protein in frog rods. 133 15