Pleckstrin Homology Domain Containing Family A, Member 1 (PLEKHA1)

The last 3 C-terminal amino acids of TAPP1 are predicted to interact with PDZ domain-containing proteins. TAPP1 and TAPP2 share 58% identity over the first 300 amino acids, which encompass both PH domains. There is little homology in the C termini. Northern blot analysis detected a 4.0-kb transcript expressed in all tissues examined, with highest levels in skeletal muscle, spleen, lung, thymus, and placenta.

TAPP1 possessed a 5-fold higher affinity for PtdIns(3,4)P2 than TAPP2. Mutation of the conserved arg212 to leucine within the PPBM of the second PH domain of TAPP1 reduced or eliminated PtdIns(3,4)P2 binding. The N-terminal PH domain contributed to the affinity with which the C-terminal PH domain bound to PtdIns(3,4)P2.