GCP4 Antibody

Structure and Function of GCP4

GCP4 is a component of the γ-tubulin complex, which includes γ-tubulin and other γ-TuRC proteins (GCP2–GCP6). This complex is vital for microtubule nucleation at the centrosome and other microtubule-organizing centers . Key structural and functional features:

• Role in Mitosis: GCP4 stabilizes γ-tubulin ring complexes (γ-TuRCs), enabling proper spindle assembly during mitosis. Depletion of GCP4 disrupts spindle formation, leading to monopolar or multipolar spindles and cell division defects .

• Autophagy Regulation: GCP4 inhibits autophagy by competing with ATG3 for binding to ATG7, thereby blocking LC3B lipidation and reducing autophagosome formation .

• Retinal Homeostasis: Haploinsufficiency of GCP4 (e.g., in heterozygous Tubgcp4 knockout mice) causes photoreceptor degeneration and retinopathy due to impaired γ-TuRC assembly and dysregulated autophagy .

1. Western Blotting:

   • Detects GCP4 in lysates from NIH 3T3 cells (predicted band: 76 kDa) .

   • Used to study GCP4 expression in retinal tissues and its interaction with ATG7 .

2. Immunocytochemistry/Immunofluorescence:

   • Visualizes GCP4 localization at the centrosome and spindle poles during mitosis .

   • Confirms colocalization with α-tubulin in 293T cells .

3. Immunohistochemistry:

   • Analyzes GCP4 expression in frozen retinal sections to assess retinopathy in Tubgcp4 heterozygous mice .

Role in Mitotic Spindle Assembly

• Mechanism: GCP4 binds γ-tubulin and stabilizes γ-TuRCs, ensuring proper spindle formation. Knockdown or depletion leads to spindle defects and mitotic arrest .

• Disease Implications: Abnormal spindle assembly due to GCP4 dysfunction may contribute to chromosomal instability and tumorigenesis .

Autophagy Regulation

• Molecular Interaction: GCP4 competes with ATG3 for ATG7 binding, blocking LC3B lipidation and autophagy initiation .

• Retinopathy Model: In Tubgcp4 heterozygous mice, reduced GCP4 levels increase ATG7 availability, enhancing autophagy and photoreceptor degeneration. Pharmacological inhibition of autophagy (e.g., with hydroxychloroquine) rescues retinal function .

Clinical and Therapeutic Potential

• Retinopathy Treatment: Targeting GCP4 or autophagy pathways may offer therapeutic strategies for retinal degeneration .

• Cancer Research: While not directly studied for GCP4, γ-TuRC components are implicated in cancer cell proliferation. GCP4 antibodies could aid in investigating its role in tumorigenesis .

Antibody Validation and Optimization