Action myoclonus-renal failure syndrome (AMRF) is caused by mutations in the lysosomal integral membrane protein type 2 (LIMP-2/SCARB2). LIMP-2 was identified as a sorting receptor for b- glucocerebrosidase (b-GC), which is defective in Gaucher disease. To date, six AMRF-causing mutations have been described, including splice site, missense and nonsense mutations. All mutations investigated in this study lead to a retention of LIMP-2 in the Endoplasmic Reticulum (ER) but affect the binding to b-GC differentially. From the three nonsense mutations only the Q288X mutation was still able to bind to b-GC as efficiently as compared to wild type LIMP-2 whereas the W146SfsX16 and W178X mutations lost their b-GC binding capacity almost completely. The LIMP-2 segment 145-288, comprising the nonsense mutations, contains a highly conserved coiled-coil domain, which we suggest determines b-GC binding. In fact, disruption of the helical arrangement and amphiphatic nature of the coiled-coil domain abolishes b-GC binding and a synthetic peptide comprising the coiled-coil domain of LIMP-2 displays pH-selective multimerisation properties. In contrast to the reduced binding properties of the nonsense mutations, the only missense mutation (H363N) found in AMRF leads to increased binding of b-GC to LIMP-2 indicating that this highly conserved histidine modifies the affinity of LIMP-2 to its ligand. With the present study we demonstrate for the first time that disruption of the coiled-coil structure or AMRF disease-causing mutations abolishes b-GC binding, indicating the importance of an intact coiled-coil structure for the interaction of LIMP-2 and b-GC.