Fig. 3.

PIP₂ binding increases membrane-associated tubulin (Tub). A, Membranes from Sf9 cells expressing m1 muscarinic receptors, Gαq, and PLCβ₁ (20 μg of membrane protein) were incubated with 300 nm tubulin–[³²P]AAGTP with or without 100 μm carbachol, 30 μmPIP₂, or both for 5 min at 23°C, followed by UV irradiation, SDS-PAGE (50 μg of membrane protein in eachlane), and autoradiography. A representative of three similar experiments performed in triplicate is shown. B, Membranes from SK-N-SH cells (40 μg of membrane protein) were incubated with tubulin–[³²P]AAGTP or carbachol, PIP₂, or both under the conditions described above. A representative of two identical experiments performed in triplicate with similar results is shown.