An Asn > Lys substitution in saposin B involving a conserved amino acidic residue and leading to the loss of the single N-glycosylation site in a patient with metachromatic leukodystrophy and normal arylsulphatase A activity

Stefano Regis, Mirella Filocamo, Fabio Corsolini, Francesco Caroli, Joke L M Keulemans, Otto P. Van Diggelen, Rosanna Gatti

Research output: Contribution to journalArticle

Abstract

Sphingolipid activator proteins are small glycoproteins required for the degradation of sphingolipids by specific lysosomal hydrolases. Four of them, called saposins, are encoded by the prosaposin gene, the product of which is proteolytically cleaved into the four mature saposin proteins (saposins A, B, C, D). One of these, saposin B, is necessary in the hydrolysis of sulphatide by arylsulphatase A where it presents the solubilised substrate to the enzyme. As an alternative to arylsulphatase A deficiency, deficiency of saposin B causes metachromatic leukodystrophy. We identified a previously undescribed mutation (N215K) in the prosaposin gene of a patient with metachromatic leukodystrophy but with normal arylsulphatase A activity and elevated sulphatide in urine. The mutation involves a highly conserved amino acidic residue and abolishes the only N-glycosylation site of saposin B.

Original languageEnglish
Pages (from-to)125-130
Number of pages6
JournalEuropean Journal of Human Genetics
Volume7
Issue number2
Publication statusPublished - Feb 1999

Keywords

  • Cerebroside sulphate activator
  • Metachromatic leukodystrophy
  • Sphingolipid activator proteins

ASJC Scopus subject areas

  • Genetics(clinical)

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