Structural and dynamical changes in an alpha-subunit of a heterotrimeric G protein along the activation pathway.

ABSTRACT: The Galpha subunits of heterotrimeric G proteins (Galphabetagamma) mediate signal transduction via activation by receptors and subsequent interaction with downstream effectors. Crystal structures indicate that conformational changes in "switch" sequences of Galpha, controlled by the identity of the bound nucleotide (GDP and GTP), modulate binding affinities to the Gbetagamma subunits, receptor, and effector proteins. To investigate the solution structure and dynamics of Galphai1 through the G protein cycle, nitroxide side chains (R1) were introduced at sites in switch II and at a site in helix alpha4, a putative effector binding region. In the inactive Galphai1(GDP) state, the EPR spectra are compatible with conformational polymorphism in switch II. Upon complex formation with Gbetagamma,

SUBMITTER: Van Eps N 

PROVIDER: S-EPMC1637559 | biostudies-literature | 2006 Oct

REPOSITORIES: biostudies-literature