Subunit contributions to phosphorylation-dependent modulation of bovine rod cyclic nucleotide-gated channels.
Subunit contributions to phosphorylation-dependent modulation of bovine rod cyclic nucleotide-gated channels.
复制标题
亚基对牛视杆环核苷酸门控通道的磷酸化依赖性调节的贡献。
DOI：
10.1113/jphysiol.2003.047167
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Kramer,RichardH
中科院分区：
文献类型：
--
作者：
Molokanova,Elena;Krajewski,JeffreyL;Satpaev,Daulet;Luetje,CharlesW;Kramer,RichardH
Cyclic nucleotide‐gated (CNG) channels in rod photoreceptors transduce a decrease in cGMP into hyperpolarization during the light response. Insulin‐like growth factor‐1 (IGF‐1) increases light responses by increasing the cGMP sensitivity of CNG channels, an event mediated by a protein tyrosine phosphatase. Native rod CNG channels are heteromultimers, composed of three CNGA1 subunits and one CNGB1 subunit. Previous studies on heterologously expressed rod CNG channels show that a specific tyrosine in the CNGA1 subunit (Y498) is required for modulation by protein tyrosine phosphatases, protein tyrosine kinases and IGF‐1. Here we show that the CNGB1 subunit contains a specific tyrosine (Y1097) that is important for modulation of heteromeric channels by tyrosine phosphorylation. Direct biochemical measurements demonstrate32P‐labelling of CNGA1Y498and CNGB1Y1097. Replacement of either Y498 of CNGA1 or Y1097 of CNGB1 with phenylalanine reduces modulation, and removal of both tyrosines eliminates modulation. Unlike CNGA1, CNGB1 does not exhibit activity dependence of modulation by tyrosine phosphorylation. Hence both CNGA1 and CNGB1 subunits contribute to phosphorylation‐dependent modulation of rod CNG channels, but the phosphorylation states of the two subunits are regulated in different ways.
