Tec family protein-tyrosine kinases and pleckstrin homology domains in mast cells.
Tec family protein-tyrosine kinases (PTKs) have been recognized as a distinct subfamily for only a few years. Two of them, Btk and Emt, are tyrosine-phosphorylated and enzymatically activated upon cross-linking of the high-affinity IgE receptor (Fc epsilonRI), suggesting their involvement in mast cell activation. Since Lyn and other Src family PTKs phosphorylate Btk at Tyr-551 and activate the latter kinase, the receptor-associated Lyn seems to activate Btk in mast cells. The Btk kinase activity, on the other hand, is regulated negatively by phosphorylation by protein kinase C (PKC) that is associated with Btk via Btk's pleckstrin homology (PH) domain. PH domains also bind to phospholipids and the beta subunit of heterotrimeric GTP-binding proteins. Therefore, it has been hypothesized that PH domains play roles in membrane localization.
Kawakami
Y
Y
Division of Allergy, La Jolla Institute for Allergy and Immunology, San Diego, CA 92121, USA.
Yao
L
L
Han
W
W
Kawakami
T
T
D001665:Binding Sites; D001798:Blood Proteins / Q000276:immunology*; D008407:Mast Cells / Q000276:immunology*; D010750:Phosphoproteins; D011505:Protein-Tyrosine Kinases / Q000276:immunology*
D001798:Blood Proteins; D010750:Phosphoproteins; C039077:platelet protein P47; C089848:Tec protein-tyrosine kinase; D011505:Protein-Tyrosine Kinases