CD45 regulates tyrosine phosphorylation of CD22 and its association with the protein tyrosine phosphatase SHP-1.
J Immunol
; 162(9): 5278-86, 1999 May 01.
Article
em En
| MEDLINE
| ID: mdl-10228003
ABSTRACT
Cross-linking of CD45 induced capping and physical sequestration from CD22 leading to an increase in tyrosine phosphorylation of CD22 and SHP-1 recruitment. Additionally, CD22 isolated from a CD45-deficient B cell line exhibited increased basal/inducible tyrosine phosphorylation and enhanced recruitment of SHP-1 compared with CD22 isolated from CD45-positive parental cells. Subsequent experiments were performed to determine whether enhanced SHP-1 recruitment to CD22 is responsible for attenuation of receptor-mediated Ca2+ responses in CD45-deficient cells. Catalytically inactive SHP-1 expressed in CD45-deficient cells interacted with CD22 and decreased phosphatase activity in CD22 immunoprecipitates to levels that were comparable to those in CD45-positive cells. Expression of catalytically inactive SHP-1 restored intracellular mobilization of Ca2+ in response to MHC class II cross-linking, but did not affect B cell Ag receptor- or class II-mediated Ca2+ influx from the extracellular space. These results indicate that CD45 regulates tyrosine phosphorylation of CD22 and binding of SHP-1. The data further indicate that enhanced recruitment and activation of SHP-1 in CD45-deficient cells affect intracellular mobilization of Ca2+, but are not responsible for abrogation of receptor-mediated Ca2+ influx from the extracellular space.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Tirosina
/
Antígenos de Diferenciação de Linfócitos B
/
Antígenos CD
/
Moléculas de Adesão Celular
/
Proteínas Tirosina Fosfatases
/
Antígenos Comuns de Leucócito
/
Lectinas
Tipo de estudo:
Risk_factors_studies
Limite:
Animals
Idioma:
En
Revista:
J Immunol
Ano de publicação:
1999
Tipo de documento:
Article
País de afiliação:
Estados Unidos