PLC beta 3 Gq: Difference between revisions
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PLC-β3 interacts with a surface on Gαq that <scene name='70/701452/Fig5/1'>overlaps almost completely</scene> with portions of Gα subunits needed for engagement of RGS proteins and the effector-binding region. Other effectors are known to engage the <scene name='70/701452/Fig3/1'>effector-binding site</scene> within Gα subunits. There are a large family of regulator of G protein signaling (RGS) proteins that independently accelerates the GTP hydrolysis in the <scene name='70/701452/Fig4/1'>GTPase domain</scene>. | PLC-β3 interacts with a surface on Gαq that <scene name='70/701452/Fig5/1'>overlaps almost completely</scene> with portions of Gα subunits needed for engagement of RGS proteins and the effector-binding region. Other effectors are known to engage the <scene name='70/701452/Fig3/1'>effector-binding site</scene> within Gα subunits. There are a large family of regulator of G protein signaling (RGS) proteins that independently accelerates the GTP hydrolysis in the <scene name='70/701452/Fig4/1'>GTPase domain</scene>. | ||
The canonical Gα effector-binding region of Gαq, located between α3 and switch 2, is occupied by a helix-turn-helix (Hα1/Hα2) that immediately follows the C2 domain of PLC- β3. <scene name='70/701452/Pro862/1'>Pro862</scene> of PLC- β3 lies within the turn between Hα1 and Hα2, makes extensive contacts with multiple residues of Gαq, and forms the center of a Gαq-binding interface. | |||
The loop between the end of the TIM barrel and the beginning of the C2 domain comprises a second distinct segment of PLC- β3 that makes extensive contacts with active Gαq, including switches 1 and 2. This interface includes a series of interdigitated pairs of charged residues, specifically in PLC- β3-Gαq Asp709/Arg202, Lys710/Glu191, and Asp721/Lys41; these in turn are supported by additional charged residues Glu703 and Arg707 of PLC- β3. | |||
An extended loop between EF hands 3 and 4 of PLC- β3 interacts with the GTP-binding region of Gαq. Asn260 of the EF3/4 loop promotes GTP hydrolysis by interaction with the side chain of Gln209 of Gαq, which rearranges during GTP hydrolysis to stabilize the transition state mimicked by GDP•AlF4–•H20. Asn260 also interacts with Glu212 to stabilize switch 1 for GTP hydrolysis. | |||
Asn260 is located at the active site of Gαq as part of a tight turn of PLC- β3 that is stabilized by Glu261 and underpinned by an extensive series of hydrogen bonds principally mediated by Asp256, Arg255 and Arg258. These residues are highly conserved in all PLC- βs, as are Asn251 and Leu267, which appear crucial in stabilizing the ends of the loop. | |||
</StructureSection> | </StructureSection> | ||
== References == | == References == | ||
<references/> | <references/> | ||