Actin filament capping protein (CapZ) (CapZ)

Actin filament capping protein, also known as CapZ, is a heterodimeric protein complex composed of alpha and beta subunits that plays a vital role in regulating actin cytoskeleton dynamics (UniProt, Wikipedia). By binding to the barbed (fast-growing) ends of actin filaments with high affinity, it blocks the addition and loss of actin monomers, thereby controlling filament length and stability (PMC, NIH). This capping activity is essential for the formation of branched actin networks during cell motility and for tethering thin filaments to the Z-disk in muscle sarcomeres (PubMed). Furthermore, it mediates crosstalk between the actin and microtubule cytoskeletons by antagonizing nucleation factors like mDia1 (PMC). In disease states, dysregulation of CapZ subunits is associated with cancer metastasis, myopathies, and developmental defects such as cleft palate (PubMed, GeneCards). For instance, CAPZA1 acts as a prognostic marker in hepatocellular and gastric cancers, where it modulates the epithelial-mesenchymal transition (PubMed). While no drugs are currently approved to target this protein in the clinic, it remains an active area of research for potential therapies in oncology and cardiology (PMC). Systemic inhibition poses significant safety concerns, including potential cardiotoxicity and severe muscle weakness due to the protein's fundamental role in maintaining cellular and sarcomeric integrity (Wikipedia).

Other names

Capping proteinCPF-actin-capping proteinBeta-actininCapping actin protein of muscle Z-lineCAPZA1CAPZB

High-affinity binding to the barbed (plus) ends of actin filaments to inhibit the exchange of actin subunits, thereby regulating filament length and stability (UniProt, PMC).