Saposin-like type B, region 1 (IPR007856)

Short name: SapB_1

Overlapping homologous superfamilies

Domain relationships



Synonym(s):cerebroside sulphate activator, CSAct

Saposin B is a small non-enzymatic glycoprotein required for the breakdown of cerebroside sulphates (sulphatides) in lysosomes. Saposin B contains three intramolecular disulphide bridges, exists as a dimer and is remarkably heat, protease, and pH stable. The crystal structure of human saposin B reveals an unusual shell-like dimer consisting of a monolayer of alpha-helices enclosing a large hydrophobic cavity. Although the secondary structure of saposin B is similar to that of the known monomeric members of the saposin-like superfamily, the helices are repacked into a different tertiary arrangement to form the homodimer. A comparison of the two forms of the saposin B dimer suggests that extraction of target lipids from membranes involves a conformational change that facilitates access to the inner cavity [PMID: 12518053].

GO terms

Biological Process

GO:0006629 lipid metabolic process

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.