MT nucleation from γ-tubulin complexes, located at centrosome, is an essential step in the formation of MT cytoskeleton. In mammalian cells, -tubulin is encoded by two genes. We functionally characterized two γ-tubulin proteins and have found that both are functionally equivalent. γ-Tubulin 2 is able to substitute for γ-tubulin 1 in MT nucleation. However, we revealed that unlike TUBG1, TUBG2 expression is downregulated in mouse preimplantation development. Mast cells represent effectors of the allergy reaction. Their activation by antigen induces number of cellular processes such as degranulation, proliferation and cytoskeleton rearrangements. The regulatory mechanisms of MT reorganization during mast cell activation are unknown. We identified new signaling proteins, GIT1 and PIX that interact with - tubulin. Depletion of GIT1 or PIX leads to changes in MT nucleation. GIT1 is phosphorylated on tyrosine and associates with γ-tubulin in a Ca2+ -dependent manner. Our data suggested a novel signaling pathway for MT rearrangement in mast cells where tyrosine kinase-activated GIT1 and βPIX work in concert with Ca2+ signaling to regulate MT nucleation. We tested the capability of GIT1 and PIX to influence -tubulin function in more cell types. We found out that GIT1/βPIX signaling proteins together...