The Gamma-Tubulin complex is composed of Gamma Tubulin and the Gamma-Tubulin complex-associated proteins GCP2, GCP3, GCP4, GCP5 and GCP6, all of which are essential components of microtubule organizing centers. Gamma-Tubulin complex components are localized to both the centrosome, where they are involved in microtubule nucleation, and to the cytoplasm, where they exist as soluble complexes that can be recruited to the centrosome as needed. Although the GCP proteins are related, they have distinct roles which contribute to the proper function of the Gamma-Tubulin complex. GCP3 (Gamma-Tubulin complex component 3), also known as TUBGCP3 or SPBC98, localizes to the centrosome and is a ubiquitously expressed 907 amino acid member of the Gamma-Tubulin complex. Like GCP2 and Gamma Tubulin, GCP3 is conserved in all eukaryotes, suggesting that it is part of a core unit involved in eukaryotic microtubule nucleation. Three isoforms of GCP3 exist due to alternative splicing events.