We are interested in understanding the role of modulation of the cGMP-sensitivity of cyclic-nucleotide gated (CNG) channels by intrinsic factors present in the retina. Our group has identified a novel mechanism for modulating CNG channels involving changes in tyrosine phosphorylation. We have shown that the cGMP-sensitivity of CNG channels increases in intact retina after exposure to IGF- 1, a growth factor intrinsic to the retina, and is due to changes in tyrosine phosphorylation. The ability to study this phenomenon has been facilitated by the ability to express active CNG channels in Xenopus oocytes. Patches excised from oocytes expressing homomeric a-CNG channels become more sensitive to cGMP in the absence of ATP. Pharmacological evidence indicates that this modulation of cGMP-sensitivity is due to changes in tyrosine phosphorylation. CNG channels expressed in oocytes also show a marked increase in the cGMP-sensitivity after IGF- 1 treatment, indicating that the oocyte expression system may be a useful model to study this phenomenon. However, native CNG channels expressed in rod outer segments (ROS) are heterotetramers consisting of two a and two b subunits. There is no research to date concerning the b-subunit in modulation via changes in tyrosine phosphorylation. This proposal will study the mechanism of modulation of the cGMP-sensitivity of CNG channels by the b-subunit. Further studies will be done to measure directly, through biochemical methods, changes in the tyrosine phosphorylation level of the b-subunit due to exposure to growth factors, such as IGF- 1, both in oocytes and intact retina.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
7F32EY013506-04
Application #
6780575
Study Section
Special Emphasis Panel (ZRG1-MDCN-5 (01))
Program Officer
Mariani, Andrew P
Project Start
2002-04-01
Project End
Budget Start
2003-06-01
Budget End
2004-03-31
Support Year
4
Fiscal Year
2003
Total Cost
$39,852
Indirect Cost
Name
University of California Berkeley
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
124726725
City
Berkeley
State
CA
Country
United States
Zip Code
94704
Molokanova, Elena; Krajewski, Jeffrey L; Satpaev, Daulet et al. (2003) Subunit contributions to phosphorylation-dependent modulation of bovine rod cyclic nucleotide-gated channels. J Physiol 552:345-56
Krajewski, Jeffrey L; Luetje, Charles W; Kramer, Richard H (2003) Tyrosine phosphorylation of rod cyclic nucleotide-gated channels switches off Ca2+/calmodulin inhibition. J Neurosci 23:10100-6