Molecular Cloning and Functional Expression of the Potassium-Dependent Sodium–Calcium Exchanger from Human and Chicken Retinal Cone Photoreceptors
Bibliographic record
Abstract
Light causes a rapid lowering of cytosolic free calcium in the outer segments of both retinal rod and cone photoreceptors. This light-induced lowering of calcium is caused by extrusion via a Na-Ca exchanger located in the rod and cone outer segment plasma membrane and plays a key role in the process of light adaptation. The Na-Ca exchanger in retinal rod outer segment was shown earlier to be a novel Na-Ca+K exchanger (NCKX), and its cDNA was obtained by molecular cloning from several mammalian species. On the other hand, the proper identity of the retinal cone Na-Ca exchanger, in terms of both functional characteristics (e.g., requirement for and transport of potassium) and molecular identity, has not yet been elucidated. Here, we report the molecular cloning, intraretinal localization by in situ hybridization, and initial functional characterization of the chicken and human cone-specific Na-Ca exchangers. In addition we report the chicken rod-specific NCKX. We identified NCKX transcripts in both human and chicken cones and observed strong potassium-dependent Na-Ca exchange activity after heterologous expression of human and chicken cone NCKX cDNAs in cultured insect cells. In situ hybridization in chicken retina showed abundant rod NCKX transcripts only in rod photoreceptors, whereas abundant cone NCKX transcripts were found in most, if not all, cone photoreceptors and also in a subpopulation of retinal ganglion cells. A detailed comparison with the previously described retinal rod and brain NCKX cDNAs is presented.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".