Fig. 1. The structure and interacting partners of Tec kinases. (a) The domain structure of the Tec family kinases. The PH domain is involved in protein-protein and protein-phospholipid interactions. The TH domain consists of a BH domain and a PR motif. The SH3 domain binds to proline-rich regions, and in collaboration with the SH2 domain it can engage the PR motif in an intramolecular interaction. The SH2 domain binds to phosphorylated tyrosine residues. The kinase domain has tyrosine-kinase catalytic activity. The atypical Tec kinase, Rlk/Txk, has a cysteinestring motif (Cys) instead of a PH domain and lacks the BH domain. Bmx/Etk lacks the PR motif of the TH domain and has an SH3-like domain. DSrc29 has two isoforms, one of which lacks the PH and TH domains. (b) Molecules that interact with the domains of Tec kinases. Both in vivo and in vitro detected interactions are included. Some binding partners have only been demonstrated for specific Tec kinases, and these are indicated in parentheses.