The lysosomal trafficking of sphingolipid activator proteins (SAPs) is mediated by sortilin.
EMBO J
; 22(24): 6430-7, 2003 Dec 15.
Article
em En
| MEDLINE
| ID: mdl-14657016
ABSTRACT
Most soluble lysosomal proteins bind the mannose 6-phosphate receptor (M6P-R) to be sorted to the lysosomes. However, the lysosomes of I-cell disease (ICD) patients, a condition resulting from a mutation in the phosphotransferase that adds mannose 6-phosphate to hydrolases, have near normal levels of several lysosomal proteins, including the sphingolipid activator proteins (SAPs), GM2AP and prosaposin. We tested the hypothesis that SAPs are targeted to the lysosomal compartment via the sortilin receptor. To test this hypothesis, a dominant-negative construct of sortilin and a sortilin small interfering RNA (siRNA) were introduced into COS-7 cells. Our results showed that both the truncated sortilin and the sortilin siRNA block the traffic of GM2AP and prosaposin to the lysosomal compartment. This observation was confirmed by a co-immunoprecipitation, which demonstrated that GM2AP and prosaposin are interactive partners of sortilin. Furthermore, a dominant-negative mutant GGA prevented the trafficking of prosaposin and GM2AP to lysosomes. In conclusion, our results show that the trafficking of SAPs is dependent on sortilin, demonstrating a novel lysosomal trafficking.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Glicoproteínas de Membrana
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Glicoproteínas
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Lisossomos
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Proteínas do Tecido Nervoso
Limite:
Animals
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Humans
Idioma:
En
Ano de publicação:
2003
Tipo de documento:
Article