The γ-tubulin gene family in humans

Despite the central role of γ-tubulin in the organization of the microtubule cytoskeleton, the γ-tubulin gene family in humans has not been characterized. We now report the identification of a second expressed human γ-tubulin gene (TUBG2) and a γ-tubulin pseudogene (TUBG1P) in addition to the previously identified γ-tubulin gene (TUBG1). Evidence from Southern hybridizations suggests that there are probably no additional γ-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, and the two genes are coexpressed in a variety of tissues. Previous studies of γ-tubulin in human tissues and cell lines have been based on the tacit assumption that a single γ-tubulin (the γ-tubulin encoded by TUBG1) was present. While this assumption is not correct, the similarity of the products of TUBG1 and TUBG2 suggests that results of previous immunolocalization and immunoprecipitation studies in human cells and tissues are likely to be valid. In addition, any pharmacological agents that target one human γ-tubulin are likely to target both. (C) 2000 Academic Press.