Residual cone vision without alpha-transducin.
Behavioral experiments in humans with a rare genetic mutation that compromises the function of alpha-transducin (Galpha the alpha-subunit of the G-protein in the primary cone phototransduction cascade) reveal a residual cone response only viable at high light levels and at low temporal frequencies....
| Những tác giả chính: | , , , , , |
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| Định dạng: | Journal article |
| Ngôn ngữ: | English |
| Được phát hành: |
2007
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| _version_ | 1826291864406327296 |
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| author | Stockman, A Smithson, H Michaelides, M Moore, A Webster, A Sharpe, LT |
| author_facet | Stockman, A Smithson, H Michaelides, M Moore, A Webster, A Sharpe, LT |
| author_sort | Stockman, A |
| collection | OXFORD |
| description | Behavioral experiments in humans with a rare genetic mutation that compromises the function of alpha-transducin (Galpha the alpha-subunit of the G-protein in the primary cone phototransduction cascade) reveal a residual cone response only viable at high light levels and at low temporal frequencies. It has three characteristic properties. First, it limits temporal frequency sensitivity to the equivalent of a simple first order reaction with a time constant of approximately 140 ms. Second, it delays the visual response by an amount that is also consistent with such a reaction. Third, it causes temporal acuity to be linearly related to the logarithm of the amount of bleached pigment. We suggest that these properties are consistent with the residual function depending on a sluggishly generated cone photobleaching product, which we tentatively identify as a cone metarhodopsin. By activating the transduction cascade, this bleaching product mimics the effects of real light and is therefore one of the molecular origins of "background equivalence," the long-established observation that the aftereffects of photopigment bleaches and the effects of real background lights are equivalent. Alternative explanations for the residual cone response include the possibilities that there is a secondary phototransduction mechanism that bypasses alpha-transduction, or that the truncated alpha-transduction that results from the mutation retains some minimal functionality. |
| first_indexed | 2024-03-07T03:05:53Z |
| format | Journal article |
| id | oxford-uuid:b27fea3c-0dc3-4944-8f63-551bd575aadc |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T03:05:53Z |
| publishDate | 2007 |
| record_format | dspace |
| spelling | oxford-uuid:b27fea3c-0dc3-4944-8f63-551bd575aadc2022-03-27T04:12:11ZResidual cone vision without alpha-transducin.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:b27fea3c-0dc3-4944-8f63-551bd575aadcEnglishSymplectic Elements at Oxford2007Stockman, ASmithson, HMichaelides, MMoore, AWebster, ASharpe, LTBehavioral experiments in humans with a rare genetic mutation that compromises the function of alpha-transducin (Galpha the alpha-subunit of the G-protein in the primary cone phototransduction cascade) reveal a residual cone response only viable at high light levels and at low temporal frequencies. It has three characteristic properties. First, it limits temporal frequency sensitivity to the equivalent of a simple first order reaction with a time constant of approximately 140 ms. Second, it delays the visual response by an amount that is also consistent with such a reaction. Third, it causes temporal acuity to be linearly related to the logarithm of the amount of bleached pigment. We suggest that these properties are consistent with the residual function depending on a sluggishly generated cone photobleaching product, which we tentatively identify as a cone metarhodopsin. By activating the transduction cascade, this bleaching product mimics the effects of real light and is therefore one of the molecular origins of "background equivalence," the long-established observation that the aftereffects of photopigment bleaches and the effects of real background lights are equivalent. Alternative explanations for the residual cone response include the possibilities that there is a secondary phototransduction mechanism that bypasses alpha-transduction, or that the truncated alpha-transduction that results from the mutation retains some minimal functionality. |
| spellingShingle | Stockman, A Smithson, H Michaelides, M Moore, A Webster, A Sharpe, LT Residual cone vision without alpha-transducin. |
| title | Residual cone vision without alpha-transducin. |
| title_full | Residual cone vision without alpha-transducin. |
| title_fullStr | Residual cone vision without alpha-transducin. |
| title_full_unstemmed | Residual cone vision without alpha-transducin. |
| title_short | Residual cone vision without alpha-transducin. |
| title_sort | residual cone vision without alpha transducin |
| work_keys_str_mv | AT stockmana residualconevisionwithoutalphatransducin AT smithsonh residualconevisionwithoutalphatransducin AT michaelidesm residualconevisionwithoutalphatransducin AT moorea residualconevisionwithoutalphatransducin AT webstera residualconevisionwithoutalphatransducin AT sharpelt residualconevisionwithoutalphatransducin |