The γ-Tubulin complex is composed of γ Tubulin and the γ-Tubulin complexassociated proteins GCP2, GCP3, GCP4, GCP5 and GCP6, all of which are essential components of microtubule organizing centers. γ-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 γ-Tubulin complex. GCP5 (γ-Tubulin complex component 5), also known as TUBGCP5, is a 1,024 amino acid member of the γ-Tubulin complex and is highly expressed in heart and skeletal muscle. Defects in the gene encoding GCP5 are implicated in Prader-Willi syndrome (PWS), a rare genetic disorder associated with obesity, compulsive behavior and lower intellectual ability.