Crystal structure of saposin D in an open conformation.
Gebai, A., Gorelik, A., Nagar, B.(2018) J Struct Biol 204: 145-150
- PubMed: 30026085 
- DOI: https://doi.org/10.1016/j.jsb.2018.07.011
- Primary Citation of Related Structures:  
5U85 - PubMed Abstract: 
Saposins are accessory proteins that aid in the degradation of sphingolipids by hydrolytic enzymes. Their structure usually comprises four α-helices arranged in various conformations including an open, V-shaped form that is generally associated with the ability to interact with membranes and/or enzymes to accentuate activity. Saposin D is required by the lysosomal hydrolase, acid ceramidase, which breaks down ceramide into sphingosine and free fatty acid, to display optimal activity. The structure of saposin D was previously determined in an inactive conformation, revealing a monomeric, closed and compact form. Here, we present the crystal structure of the open, V-shaped form of saposin D. The overall shape is similar to the open conformation found in other saposins with slight differences in the angles between the α-helices. The structure forms a dimer that serves to stabilize the hydrophobic surface exposed in the open form, which results in an internal, hydrophobic cavity that could be used to carry extracted membrane lipids.
- Department of Biochemistry and Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC H3G 0B1, Canada.
Organizational Affiliation: 
















