The involvement of p38γ in the regulation of nuclear and cytoplasmic protein complexes. In the nucleus of resting cells SAP97/hDlg complexes with PSF/p54-RNAs, whereas in the cytoplasm it interacts at the cytoskeleton with both the protein GKAP and a fraction of p38γ, which is localized mainly in the cytoplasm. Changes in the osmolarity of the environment causes: (i) p38γ activation in the cytoplasm, which phosphorylates SAP97/hDlg causing its dissociation from GKAP and therefore from the cytoskeleton, (ii) accumulation of p38γ in the nucleus, and (iii) the nuclear interaction of p38γ with SAP97/hDlg, which leads to its dissociation from PSF/p54-RNAs independently of SAP97/hDlg phosphorylation.
