DNAJA3 A gene on chromosome 16p13.3 that encodes a protein which, depending on the isoform, up- or downregulates apoptotic signal transduction. DNAJA3 affects cytochrome c release from mitochondria and caspase 3 activation. It also modulates IFN-gamma-mediated transcriptional activity. Isoform 1 upreguates TNF-induced apoptosis; isoform 2 downregulates apoptosis. Isoform 2 may play a role in neuromuscular junction development as an effector of the MUSK signalling pathway. DNAJA3 is highly expressed in the heart, liver, lungs and skeletal muscle.