Guanine Nucleotide-Binding Protein Subunit Beta-4 (GNB4)

GNB4 encodes a beta subunit of heterotrimeric G proteins, molecular transducers essential for transmembrane signaling. The beta and gamma chains work together to regulate GTPase activity, facilitate GDP-GTP exchange, and enable G protein-effector interactions (UniProt: Q9HAV0). G protein signaling cascades are fundamental to cellular communication across numerous physiological systems.

In the peripheral nervous system, GNB4 mutations are associated with Charcot-Marie-Tooth disease, dominant intermediate F (CMTDIF; MIM 615185), a progressive disorder characterized by distal muscle weakness and atrophy with variable nerve conduction velocities (UniProt: Q9HAV0). This connection underscores the protein's role in neuronal function and maintenance.

GNB4 is upregulated in post-mortem Alzheimer's disease brain tissue relative to age-matched controls (Chaparral AD proteomics). Analysis of human AD brain versus control samples using TMT-labeled proteomics across four subcellular fractions yielded a mean log2 fold-change of +0.33 (Chaparral AD proteomics), suggesting modest elevation of this G protein component in the disease state. The functional significance of this increase in AD pathophysiology remains to be determined.