ATPase required for the post-translational delivery of tail-anchored (TA) proteins to the endoplasmic reticulum. Recognizes and selectively binds the transmembrane domain of TA proteins in the cytosol. This complex then targets to the endoplasmic reticulum by membrane-bound receptors GET1 and GET2, where the tail-anchored protein is released for insertion. This process is regulated by ATP binding and hydrolysis. ATP binding drives the homodimer towards the closed dimer state, facilitating recognition of newly synthesized TA membrane proteins. ATP hydrolysis is required for insertion. Subsequently, the homodimer reverts towards the open dimer state, lowering its affinity for the GET1-GET2 receptor, and returning it to the cytosol to initiate a new round of targeting. Cooperates with the HDEL receptor ERD2 to mediate the ATP-dependent retrieval of resident ER proteins that contain a C-terminal H-D-E-L retention signal from the Golgi to the ER. Involved in low-level resistance to the oxyanions arsenite and arsenate, and in heat tolerance. Homodimer. Component of the Golgi to ER traffic (GET) complex, which is composed of GET1, GET2 and GET3. Within the complex, GET1 and GET2 form a heterotetramer which is stabilized by phosphatidylinositol binding and which binds to the GET3 homodimer (PubMed:32910895). Interacts with the chloride channel protein GEF1. GET1 and GET2 are required for targeting GET3 to the endoplasmic reticulum. Present with 17300 molecules/cell in log phase SD medium. Belongs to the arsA ATPase family.