| First Author | Wen XH | Year | 2012 |
| Journal | Cell Physiol Biochem | Volume | 29 |
| Issue | 3-4 | Pages | 417-30 |
| PubMed ID | 22508049 | Mgi Jnum | J:312763 |
| Mgi Id | MGI:6782406 | Doi | 10.1159/000338496 |
| Citation | Wen XH, et al. (2012) S100B serves as a Ca(2+) sensor for ROS-GC1 guanylate cyclase in cones but not in rods of the murine retina. Cell Physiol Biochem 29(3-4):417-30 |
| abstractText | Rod outer segment membrane guanylate cyclase (ROS-GC1) is a bimodal Ca(2+) signal transduction switch. Lowering [Ca(2+)](i) from 200 to 20 nM progressively turns it "ON" as does raising [Ca(2+)](i) from 500 to 5000 nM. The mode operating at lower [Ca(2+)](i) plays a vital role in phototransduction in both rods and cones. The physiological function of the mode operating at elevated [Ca(2+)](i) is not known. Through comprehensive studies on mice involving gene deletions, biochemistry, immunohistochemistry, electroretinograms and single cell recordings, the present study demonstrates that the Ca(2+)-sensor S100B coexists with and is physiologically linked to ROS-GC1 in cones but not in rods. It up-regulates ROS-GC1 activity with a K(1/2) for Ca(2+) greater than 500 nM and modulates the transmission of neural signals to cone ON-bipolar cells. Furthermore, a possibility is raised that under pathological conditions where [Ca(2+)](i) levels rise to and perhaps even enter the micromolar range, the S100B signaling switch will be turned "ON" causing an explosive production of CNG channel opening and further rise in [Ca(2+)](i) in cone outer segments. The findings define a new cone-specific Ca(2+)-dependent feature of photoreceptors and expand our understanding of the operational principles of phototransduction machinery. |
