PAK3 Protein, Human (Active, sf9, His)

PAK3, a serine/threonine protein kinase, assumes a pivotal role in diverse signaling pathways, influencing cytoskeleton dynamics, cell migration, and cell cycle regulation. Its involvement in dendritic spine morphogenesis, synapse formation, and plasticity underscores its significance in neuronal processes. As a downstream effector of small GTPases CDC42 and RAC1, PAK3 undergoes activation through their binding, triggering autophosphorylation on multiple serine and/or threonine residues. The kinase activity of PAK3 extends to phosphorylating MAPK4 and MAPK6, activating the downstream target MAPKAPK5, which modulates F-actin polymerization and cell migration. Furthermore, PAK3 phosphorylates TNNI3/troponin I, impacting calcium sensitivity and relaxation kinetics of thin myofilaments. Its indispensable role in early neuronal development is evident, particularly in hippocampal neurons, where it facilitates dendritic spine formation and excitatory synapse establishment, possibly by regulating actomyosin contractility through myosin II regulatory light chain phosphorylation. The multifaceted functions of PAK3 highlight its intricate contributions to cellular processes critical for neuronal structure and function.