RhoA (Ser-188), Phosphospecific Antibody

Rho (A, B, & C) proteins are members of the Ras superfamily of GTPases. These proteins regulate a variety of cellular functions, including cell cycle progression, cytoskeletal rearrangement, and gene expression. Rho cycles between the active GTP-bound form and an inactive GDP-bound form. Interconversion between these forms is controlled by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) . The Rho proteins RhoA, RhoB, and RhoC are highly homologous and contain the consensus amino acid sequences necessary for GDP/GTP-binding and GTPase activity. Post-translational regulation of Rho activity has been shown specifically for RhoA. This Rho protein is phosphorylated in vitro on serine 188 by cAMP- and cGMP-dependent kinases (PKA and PKG) . Ser-188 phosphorylation enhances RhoGDI binding and inhibits RhoA-mediated stress fiber formation. Thus, Ser-188 is an important site for negative regulation of RhoA activity.

The antibody detects a RhoA GST fusion protein when phosphorylated with PKA, but does not detect the unphosphorylated recombinant protein. This peptide sequence is highly conserved in rat, mouse, and chicken RhoA, but is not found in RhoB or RhoC proteins.