Pleckstrin homology domains of Tec family protein kinases

Pleckstrin homology (PH) domains have been shown to be involved in different interactions, including binding to inositol compounds, protein kinase C isoforms, and heterotrimer ic G proteins. In some cases, the most important function of PH domains is: transient localisation of proteins to membranes, where they can interact with their partners. Tec family protein tyrosine kinases contain a PH domain. In Btk, also PH domain mutations lead into an immunodeficiency, X-linked agammaglobulinemia (XLA). A new disease-causing mutation was identified in the PH domain. The structures for the PH domains of Bmx, Ph, and Tec were modelled based on Btk structure. The domains seem to have similar scaffolding and electrostatic polarisation but to have some differences in the binding regions. The models provide new insight into the specificity, function,, and regulation of Tec family kinases. (C) 1999 Academic Press.