| First Author | Ulyanova T | Year | 1999 |
| Journal | Eur J Immunol | Volume | 29 |
| Issue | 11 | Pages | 3440-9 |
| PubMed ID | 10556798 | Mgi Jnum | J:273610 |
| Mgi Id | MGI:6294631 | Doi | 10.1002/(SICI)1521-4141(199911)29:11<3440::AID-IMMU3440>3.0.CO;2-C |
| Citation | Ulyanova T, et al. (1999) The sialoadhesin CD33 is a myeloid-specific inhibitory receptor. Eur J Immunol 29(11):3440-9 |
| abstractText | Activating and inhibitory receptors act in concert to regulate cellular activation. Inhibitory receptors are characterized by the presence of a characteristic sequence known as an immunoreceptor tyrosine-based inhibitory motif (ITIM) in their cytoplasmic tail. Phosphorylated ITIM serve as docking sites for the SH2-containing phosphatases which then inhibit signal transduction. CD33 is a member of the immunoglobulin superfamily and contains two immunoglobulin-like domains, a transmembrane region and a cytoplasmic tail that has two potential ITIM sequences. CD33 expression is restricted to cells of myelomonocytic lineage. The precise function of CD33 is unknown although it is a lectin that binds sialic acid residues in N- and O-glycans on cell surfaces. Co-immunoprecipitation studies demonstrate that CD33 associates with the SH2-containing tyrosine phosphatase SHP-1 in monocytes. The proximal ITIM is necessary and sufficient for SHP-1 binding which is mediated by the aminoterminal SH2 domain. Treatment of SHP-1 with a phosphopeptide representing the proximal CD33 ITIM results in increased SHP-1 enzymatic activity. CD33 exerts an inhibitory effect on tyrosine phosphorylation and Ca(2+) mobilization when co-engaged with the activating FcgammaRI receptor. This data indicates that CD33 is an inhibitory receptor that may regulate FcgammaRI signal transduction. |
