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MIR16, a putative membrane glycerophosphodiester phosphodiesterase, interacts with RGS16
B Zheng1, D Chen, M G Farquhar
1Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093-0651, USA.
Abstract:
We have identified the protein MIR16 (for Membrane Interacting protein of RGS16) from a yeast two-hybrid screen by using RGS16 as bait. MIR16 shares strong homology with bacterial glycerophosphodiester phosphodiesterases. It interacts with RGS16 and, more weakly, with several other selected RGS proteins. Analysis of deletion mutants showed that the N-terminal region of the RGS domain in RGS16 is required for its interaction with MIR16. MIR16 is an integral membrane glycoprotein, because it remained associated with membrane fractions after alkaline treatment and because, in some cells, it is sensitive to digestion with endoglycosidase H. By immunofluorescence and immunoelectron microscopy, MIR16 was localized on the plasma membrane in liver and kidney and on intracellular membranes in rat pituitary and cultured pituitary cells. MIR16 represents the only integral membrane protein identified thus far to interact with an RGS domain and, to our knowledge, is the only mammalian glycerophosphodiester phosphodiesterase that has been cloned. The putative enzymatic activity of MIR16 and its interaction with RGS16 suggest that it may play important roles in lipid metabolism and in G protein signaling.
Insights
Researchers identified MIR16, a novel membrane protein interacting with RGS proteins, potentially impacting lipid metabolism and G protein signaling. This discovery advances understanding of cellular communication and enzyme function.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Regulator of G protein signaling (RGS) proteins are crucial regulators of G protein signaling pathways.
- Integral membrane proteins play vital roles in cellular communication and signal transduction.
Purpose of the Study:
- To identify novel proteins interacting with RGS16.
- To characterize the function and localization of the identified interacting protein, MIR16.
Main Methods:
- Yeast two-hybrid screening was employed to identify interacting proteins.
- Deletion mutant analysis was used to map interaction domains.
- Biochemical assays (alkaline treatment, endoglycosidase H digestion) and microscopy (immunofluorescence, immunoelectron microscopy) were used for protein characterization and localization.
Main Results:
- MIR16 (Membrane Interacting protein of RGS16) was identified as an interacting partner of RGS16.
- MIR16 exhibits homology to bacterial glycerophosphodiester phosphodiesterases and interacts with RGS16 and other RGS proteins.
- MIR16 is an integral membrane glycoprotein localized to the plasma membrane and intracellular membranes.
- The N-terminal region of the RGS domain in RGS16 is essential for MIR16 interaction.
Conclusions:
- MIR16 is the first identified integral membrane protein that interacts with an RGS domain.
- MIR16 is the first cloned mammalian glycerophosphodiester phosphodiesterase.
- The interaction of MIR16 with RGS16 suggests a role in lipid metabolism and G protein signaling pathways.