BAG3 and Spinocerebellar ataxia type 3: 46, 58, 59, 60, 61 The physiological significance for the role of BIS in protein homeostasis has been implicated in vivo by the upregulation of BIS–HspB8 complex in astrocytes of the human brain affected by protein aggregation diseases such as Huntington's diseases and spinocerebellar ataxia type 3.62 This indicates that the induction of BIS was driven by the necessity to facilitate the clearance of aggregated proteins within an aggregation-prone milieu.