Involvement of p72syk kinase, p53/561yn kinase and phosphatidyl inositol-3 kinase in signal transduction via the human B lymphocyte antigen CD22
✍ Scribed by Joseph M. Tuscano; Pablo Engel; Thomas F. Tedder; Alka Agarwal; John H. Kehrl
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 790 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0014-2980
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✦ Synopsis
Involvement of p72syk kinase, p53/56lyn kinase and phosphatidyl inositol-3 kinase in signal transduction via the human B lymphocyte antigen CD22
CD22 is a B lymphocyte-specific membrane protein that functions as an adhesion molecule via its interactions with a subset of a2-6-linked sialic acidcontaining glycoproteins. Engagement of CD22 with a monoclonal antibody (HB22.23) that blocks the binding of CD22 to its ligands results in rapid CD22 tyrosine phosphorylation and in increased association of CD22 with p53/561yn kinase, p85 phosphatidyl inositol-3 kinase, and p72syk kinase. Synthetic peptides that span various regions of the intracellular portion of CD22 were used to map potential kinase binding sites. All three kinases associated with a tyrosinephosphorylated peptide that spans tyrosine amino acid residues 822 and 842, implicating this as an important region in mediating CD22 signal transduction. In addition, purified pS61yn directly bound to the same peptide. Engagement of CD22 with HB22.23 was sufficient to stimulate normal B cell proliferation. This study further substantiates the importance of CD22 as a B lymphocyte signaling molecule and begins to unravel the mechanisms by which CD22 cross-linking can alter B cell function.
While CD22 probably mediates both homo-and heterotypic cell adhesion [6, 7, 11, 121, the consequences of the direct engagement of CD22 on Bcell function and signal transduction pathways are largely unknown. Previous