The scaffold protein RACK1 regulates root growth and gravitropic response by recruiting PINOID to phosphorylate the auxin efflux transporter PIN‐FORMED2

The scaffolding protein RACK1 is involved in polar auxin transport and signaling. It binds to PINOID and PIN-FORMED2, enhancing their interaction and phosphorylation-dependent auxin efflux. Knocking down RACK1 genes impairs auxin-related processes such as root growth and gravitropic response.