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/lp/annual-reviews/the-cd19-cr2-tapa-1-complex-of-b-lymphocytes-linking-natural-to-Y8SpXNRRyg
- Publisher
- Annual Reviews
- Copyright
- Copyright 1995 Annual Reviews. All rights reserved
- Subject
- Review Articles
- ISSN
- 0732-0582
- eISSN
- 1545-3278
- DOI
- 10.1146/annurev.iy.13.040195.001015
- pmid
- 7542009
- Publisher site
- See Article on Publisher Site
Abstract
signal transd uction , Blymphocytes must respond to low concentrations of antigen despite having low affinity antigen receptors during the primary immune response. CDI9, a B cell-restricted membrane protein of the immunoglobulin superfamily that associates with the antigen receptor complex, may help the B cell meet this requirement. Cross-linking CD19 to membrane immunoglobulin (mIg) lowers, by two orders of magnitude, the number of mIg that must be ligated to activate phospholipase C (PLC) or to induce DNA synthesis. CD19 is coupled, via pro tein tyrosine kinases (PTKs), to PLC and phosphatidylinositol 3' kinase (pI3' kinase), and it interacts with the Src-type nonreceptor PTK lyn. It also associates with two other membrane proteins, CR2 (complement receptor type 2, CD2l), which permits nonimmunologic ligation of CD19, and TAPA-I, a member of the tetraspan family of membrane proteins. CR2 binds fragments of C3 that are covalently attached to glycoconjugates. This indirectly enables CD l9 to be cross linked to mIg after preimmune recognition of an immunogen by the complement system. CR2 also can be ligated by CD23, a lectin-like membrane protein that resides on cells that may present antigen to B cells. TAPA-I associates with several other membrane proteins on Band
Journal
Annual Review of Immunology – Annual Reviews
Published: Apr 1, 1995