ABCA1 and prion disease: Furthermore, key enzymes and transporters, such as transglutaminase 1 (Tgm1) and ATP binding cassette subfamily A member 1 (ABCA1) that have been implicated in the clearance of misfolded protein (33, 34), were up-regulated in murine prion disease (Fig. 2B and data file S1, sheet 2).