Enables Hsp70 protein binding activity and chaperone binding activity. Involved in B cell differentiation; positive regulation of immunoglobulin production; and ubiquitin-dependent ERAD pathway. Located in endoplasmic reticulum lumen. Is expressed in several structures, including alimentary system; integumental system; nervous system; respiratory system; and sensory organ. Orthologous to human DNAJB9 (DnaJ heat shock protein family (Hsp40) member B9). [provided by Alliance of Genome Resources, Apr 2022]