Co-chaperone which acts as a regulator of the Hsp70 chaperone machinery and may be involved in the processing of other ataxia-linked proteins. Predominantly cytoplasmic, a small portion is present in the nucleus and also shows a partial mitochondrial overlap with the mitochondrial marker Hsp60. Brain (at protein level). The ubiquitin-like domain mediates interaction with the proteasome. The J domain is functional and is able to stimulate E.coli dnaK ATPase activity. Truncated N-terminus.