Serine/threonine-protein kinase PAK 5

PAK5 (p21-activated kinase 5) is a serine/threonine protein kinase that regulates multiple cellular processes including cytoskeleton dynamics, cell migration, proliferation, and survival (UniProt: Q9P286). The protein functions downstream of growth factor receptors and small GTPases CDC42/RAC1, phosphorylating substrates such as RAF1, BAD, CTNND1, and MARK2 to modulate cell signaling and structural integrity.

PAK5 is expressed broadly across tissues and participates in pathways controlling cell morphology and microtubule stability. No primary disease associations are documented in UniProt for this protein; however, it has been identified as relevant to neurodegenerative processes through proteomics analysis.

In Alzheimer's disease, PAK5 is consistently downregulated in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics), with a mean log2 fold-change of −0.45 across examined subcellular fractions. This reduction may reflect compromised cytoskeletal regulation and cell survival signaling in AD pathology, though the functional consequence of decreased PAK5 levels in disease progression requires further investigation.