PT  - JOURNAL ARTICLE
AU  - Elena Molokanova
AU  - Bhavya Trivedi
AU  - Alexei Savchenko
AU  - Richard H. Kramer
TI  - Modulation of Rod Photoreceptor Cyclic Nucleotide-Gated Channels by Tyrosine Phosphorylation
AID  - 10.1523/JNEUROSCI.17-23-09068.1997
DP  - 1997 Dec 01
TA  - The Journal of Neuroscience
PG  - 9068--9076
VI  - 17
IP  - 23
4099  - http://www.jneurosci.org/content/17/23/9068.short
4100  - http://www.jneurosci.org/content/17/23/9068.full
SO  - J. Neurosci.1997 Dec 01; 17
AB  - Cyclic nucleotide-gated (CNG) channels in vertebrate photoreceptors are crucial for transducing light-induced changes in cGMP concentration into electrical signals. In this study, we show that both native and exogenously expressed CNG channels from rods are modulated by tyrosine phosphorylation. The cGMP sensitivity of CNG channels, composed of rod α-subunits expressed in Xenopus oocytes, gradually increases after excision of inside-out patches from the oocyte membrane. This increase in sensitivity is inhibited by a protein tyrosine phosphatase (PTP) inhibitor and is unaffected by three different Ser/Thr phosphatase inhibitors. Moreover, it is suppressed or reversed by application of ATP but not by a nonhydrolyzable ATP analog. Application of protein tyrosine kinase (PTK) inhibitors causes an increase in cGMP sensitivity, but only in the presence of ATP. Taken together, these results suggest that CNG channels expressed in oocytes are associated with active PTK(s) and PTP(s) that regulate their cGMP sensitivity by changing phosphorylation state. The cGMP sensitivity of native CNG channels from salamander rod outer segments also increases and decreases after incubation with inhibitors of PTP(s) and PTK(s), respectively. These results suggest that rod CNG channels are modulated by tyrosine phosphorylation, which may function as a novel mechanism for regulating the sensitivity of rods to light.