A Gα12-specific Binding Domain in AKAP-Lbc and p114RhoGEF.

摘要: AKAP-Lbc is a Rho-activating guanine nucleotide exchange factor (RhoGEF) important in heart development and pro-fibrotic signaling cardiomyocytes. Heterotrimeric G proteins of the G12/13 subfamily, comprising Gα12 Gα13, are well characterized as stimulating specialized group RhoGEFs through interaction with their RGS-homology (RH) domain. Despite lacking an RH domain, bound by unknown mechanism to activate Rho signaling. We identified Gα12-binding region near C-terminus AKAP-Lbc, closely homologous p114RhoGEF that we also discovered interact Gα12. This binding distinct from well-studied interface between RH-RhoGEFs α subunits, demonstrated mutants selectively impaired either this AKAP-Lbc/p114RhoGEF or RH-RhoGEFs. showed high specificity for comparison experiments using chimeric subunits mapped determinants selectivity N-terminal In cultured cells expressing constitutively GDP-bound construct was more potent exerting dominant-negative effect on serum-mediated p114RhoGEF, demonstrating coupling these cellular pathway. addition, charge-reversal conserved residues disrupted both proteins, suggesting they harbor common structural subunit. Our results provide first evidence effector, define novel allows input non-RH RhoGEFs.