The polybasic puzzle: how N-terminal charges modulate Gαi₁ membrane behavior and signaling output.

ABSTRACT: G protein-coupled receptors (GPCRs) mediate essential cellular responses through interactions with heterotrimeric G proteins, particularly the Gαi subfamily. Despite high sequence similarity among Gαi subunits, subtle differences in their N-terminal polybasic regions influence membrane association, heterotrimer stability, and downstream signaling. Here, we investigate the functional significance of two arginine residues (R21 and R32) within the N-terminal helix of Gαi₁. Using site-directed mutagenesis, fluorescence-based techniques including FRAP and FLIM-FRET, cAMP assays, and molecular dynamics simulations, we demonstrate that even charge-conserving arginine-to-lysine substitutions significantly alter membrane dynamics and impair receptor-mediated signaling. Notably, the R21A/

SUBMITTER: Mystek P 

PROVIDER: S-EPMC12751887 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature