The gamma-tubulin gene family in humans

Despite the central role of gamma-tubulin in the organization of the microt ubule cytoskeleton, the gamma-tubulin gene family in humans has not been ch aracterized. We now report the identification of a second expressed human g amma-tubulin gene (TUBG2) and a gamma-tubulin pseudogene (TUBG1P) in additi on to the previously identified gamma-tubulin gene (TUBG1). Evidence from S outhern hybridizations suggests that there are probably no additional gamma -tubulin sequences in the human genome. TUBG1 and TUBG2 are within 20 kb of each other in region q21 of chromosome 17, and TUBG1P is on chromosome 7. The proteins encoded by TUBG1 and TUBG2 share 97.3% amino acid identity, an d the two genes are coexpressed in a variety of tissues. Previous studies o f gamma-tubulin in human tissues and cell lines have been based on the taci t assumption that a single gamma-tubulin (the gamma-tubulin encoded by TUBG 1) was present. While this assumption is not correct, the similarity of the products of TUBG1 and TUBG2 suggests that results of previous immunolocali zation and immunoprecipitation studies in human cells and tissues are likel y to be valid. In addition, any pharmacological agents that target one huma n gamma-tubulin are likely to target both. (C) 2000 Academic Press.