Selective interactions between Gialpha1 and Gialpha3 and the GoLoco/GPR domain of RGS14 influence its dynamic subcellular localization.
RGS14 is a multifunctional protein that contains an RGS domain, which binds active Gi/oalpha-GTP, a GoLoco/GPR domain, which binds inactive Gialpha-GDP, and a tandem Rap1/2 binding domain (RBD). Studies were initiated to determine the roles of these domains and their interactions with Gialpha on RGS14 subcellular localization. We report that RGS14 dynamic subcellular localization in HeLa cells depends on distinct domains and selective interactions with preferred Gialpha isoforms. RGS14 shuttles rapidly between the nucleus and cytoplasm, and associates with centrosomes during interphase and mitosis. RGS14 localization to the nucleus depends on the RGS and RBD domains, its translocation out of the nucleus depends on the GoLoco/GPR domain, and its localization to centrosomes depends on the RBD domain. Gialpha subunits (Gialpha1, 2 and 3) localize predominantly at the plasma membrane. RGS14 binds directly to inactive and active forms of Gialpha1 and Gialpha3, but not Gialpha2, both as a purified protein and when recovered from cells. RGS14 localizes predominantly at the plasma membrane in cells with inactive Gialpha1 and Gialpha3, but not Gialpha2, whereas less RGS14 associates with active Gialpha1/3 at the plasma membrane. RGS14 binding to inactive, but not active Gialpha1/3 also prevents association with centrosomes or nuclear localization. Removal or functional inactivation of the GoLoco/GPR domain causes RGS14 to accumulate at centrosomes and in the nucleus, but renders it insensitive to recruitment to the plasma membrane by Gialpha1/3. These findings highlight the importance of the GoLoco/GPR domain and its interactions with Gialpha1/3 in determining RGS14 subcellular localization and linked functions.[1]References
- Selective interactions between Gialpha1 and Gialpha3 and the GoLoco/GPR domain of RGS14 influence its dynamic subcellular localization. Shu, F.J., Ramineni, S., Amyot, W., Hepler, J.R. Cell. Signal. (2007) [Pubmed]
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