TUBGCP4 is a component of the gamma-tubulin ring complex (gTuRC), the assembly that mediates microtubule nucleation. The gTuRC regulates minus-end nucleation of alpha-beta tubulin heterodimers, which then grow into microtubule protofilaments. This is a critical step in centrosome duplication and spindle formation, so the TUBGCP4 protein sits at the base of microtubule organisation in dividing cells.

In mammalian cells, TUBGCP4 localises to centrosomes in association with gamma-tubulin. Crystal structure analysis revealed a fold composed of five helical bundles arranged around conserved hydrophobic cores. An exposed surface area in the C-terminal domain is essential and sufficient for direct binding to gamma-tubulin, which explains how the subunit is anchored within the complex. The protein belongs to the TUBGCP family, and HGNC classifies the gene within the tubulin gamma complex component family. The TUBGCP4 gene also undergoes alternative splicing, producing multiple transcript variants.

TUBGCP4 was previously named tubulin, gamma complex associated protein 4, and is also referred to as GCP4. Mutations in the gene that alter microtubule organisation are associated with microcephaly and chorioretinopathy, linking gTuRC integrity to neurodevelopmental and retinal phenotypes. The mouse ortholog is designated Tubgcp4.