GRASP depletion–mediated Golgi destruction decreases cell adhesion and migration via the reduction of a5ß1 integrin

Ahat, Erpan; Xiang, Yi; Zhang, Xiaoyan; Bekier, Michael E.; Wang, Yanzhuang

As a cell surface receptor, mature α5β1 integrin is mainly localized at the plasma membrane and is dynamically internalized and recycled. Given that only those molecules at the surface are functional in cell adhesion, we performed a cell surface biotinylation and streptavidin pull-down assay. The results showed that the cell surface level of α5β1 integrin was robustly reduced in GRASP-knockout cells compared with the level in control cells ( Figure 5F ). Another plasma membrane protein, TfR, was unaffected by GRASP knockout and was also pulled down, while the cytosolic protein actin was not detected in the pull-down. As an internal control, only the glycosylated upper band of β1 integrin was isolated ( Figure 5F ). These results demonstrate that GRASP depletion reduces α5β1-integrin level at the cell surface, which subsequently decreases cell adhesion.