Transcriptional activator involved in salt and osmotic stress responses. Functions as a stress sensor and transducer in a signaling pathway that resembles an ER stress response. Following salt stress, BZIP17 is cleaved by SBT6.1 (S1P) and S2P at the C-terminus and the N-terminal bZIP component is translocated to the nucleus, where it activates the expression of salt stress response genes (PubMed:17662035). Functions as a stress sensor and transducer in ER stress signaling pathway. ER stress induces proteolysis of BZIP17 by SBT6.1 (S1P) and S2P, and the N-terminal bZIP component is translocated to the nucleus, where it activates the expression and production of ER chaperones, as well as protein involved in brassinosteroid (BR) signaling, which is required for stress acclimation and growth (PubMed:20876872). Interacts with BZIP28. Translocates to the nucleus following salt treatment, heat shock or tunicamycin treatment (ER stress) (PubMed:17662035, PubMed:20876872). Relocation of BZIP17 from ER to the nucleus occurs through the Golgi and is S2P-dependent (PubMed:20876872). No visible phenotype under normal growth conditions, but mutant plants have increased sensitivity to salt-induced osmotic stress. Belongs to the bZIP family.