| Autor: |
Katja Koeppen, Thomas Ladewig, R. E. Carpio, Bernd Wissinger, Peggy Reuter |
| Rok vydání: |
2009 |
| Předmět: |
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| Zdroj: |
Biophysical Journal. 96(3) |
| ISSN: |
0006-3495 |
| DOI: |
10.1016/j.bpj.2008.12.2439 |
| Popis: |
Cyclic nucleotide-gated (CNG) channels are a crucial component of the phototransduction cascade in vertebrate photoreceptors. The opening and closure of these channels and consequently the influx of sodium and calcium ions into the photoreceptor outer segment is directed by the intracellular light-dependent cGMP level. Cone CNG channels are heterooligomers consisting of two A3- and two B3-subunits, which are encoded by the CNGA3 and the CNGB3 gene. In both genes mutations have been identified, which can lead to a dysfunction of the CNG channels in cone photoreceptors. In humans this results in the autosomal-recessively inherited disease achromatopsia (color blindness).In order to characterize CNG channels in zebrafish, which possess four morphologically and physiologically distinct classes of cones, we have identified two homologous candidate genes for CNGA3 and two for CNGB3 by in silico database analyses. All four genes as well as a splice variant of CNGA3-1 have been cloned and were heterologously expressed in HEK293 cells. Subsequently, the zebrafish CNG channels were functionally characterized by calcium imaging and patch-clamp measurements.The retinal expression of all four genes has been confirmed by RT-PCR. In silico analyses revealed, that the two CNGA3 candidates are located at two different locations in the zebrafish genome and are presumably a result of the whole genome duplication as it is known for several genes in zebrafish. In contrast to that, the two CNGB3 candidates are located in a tandem as a result of an additional gene duplication event. ZfCNGA3-1 and zfCNGA3-2 have 62 % identity with the human CNGA3 protein. ZfCNGB3-1 has 43 % and zfCNGB3-2 has 49 % identity with human CNGB3. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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