Plexin-A4

Plexin-A4 (PLXNA4) is a transmembrane coreceptor for semaphorin 3A (SEMA3A) that functions in axon guidance and cytoskeletal remodeling (UniProt: Q9HCM2). It acts as a component of the neuropilin–plexin signaling complex, where it modulates ligand affinity and transduces downstream cytoplasmic signals essential for neuronal development and axon pathfinding in the developing nervous system.

Plexin-A4 is expressed in neural tissue and plays a fundamental role in semaphorin-mediated developmental signaling. UniProt records no curated disease associations for this protein, though its involvement in axon guidance and neuronal plasticity suggests relevance to neurological function.

In Alzheimer's disease, Plexin-A4 is upregulated in human post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics, mean log2FC = 0.41). This elevation was detected in a TMT-labeled proteomic analysis across multiple subcellular fractions, suggesting altered semaphorin signaling or compensatory cytoskeletal remodeling may accompany AD pathology, though the functional significance of this upregulation requires further investigation.