Analysis of RGSZ1 protein interaction with Galphai subunits.

RGSZ1 has been reported to interact with G-protein subunits of the Galphai family and function as a GTPase-accelerating protein on intrinsic Galphai GTPase activity. This article describes several experimental approaches and assays used to investigate the effect of RGSZ1 on Galphai subunits. The formats described here include physical and functional interaction assays by which the association of RGSZ1 with Galphai is explored both in vitro and in vivo. The methods analyzing physical interaction include pull-down and coimmunoprecipitation assays. We also apply yeast two-hybrid techniques to detect RGSZ1 protein interaction with Galpha subunits. Additionally, we developed several functional assay systems to identify the functional relationship between RGSZ1 and Galphai, such as the single turnover GTPase assay, yeast pheromone response assay, mitogen-activated protein kinase assay, and serum response element reporter assay.