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Binding of GM1 ganglioside to a synthetic peptide derived from the lysosomal sphingolipid activator protein saposin B
Author(s) -
Champagne Marie-Josée,
Lamontagne Sonia,
Potier Michel
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00717-9
Subject(s) - biochemistry , ganglioside , sphingolipid , peptide , activator (genetics) , circular dichroism , chemistry , plasma protein binding , biology , receptor
Saposin B is a lysosomal sphingolipid activator protein which activates GM1 ganglioside hydrolysis by lysosomal β‐galactosidase. To identify the structural elements of saposin B implicated in sphingolipid binding, we studied a synthetic peptide corresponding to a predicted α‐helix, sapB‐18, spanning residues 52–69 of saposin B. The circular dichroism spectrum of sapB‐18 at pH 4.4 was consistent with a 44% α‐helix content. As shown by intrinsic Tyr fluorescence studies of sapB‐18, this peptide binds the GM1 ganglioside with a K d of about 7 μM. Thus, we suggest that a putative amphipathic α‐helix between residues 52 and 69 of saposin B plays a major role in the recognition and binding of GM1 ganglioside by saposin B.