The serine/threonine protein kinase B(PKB) is related to cellular survival and regulation. PKB is composed of PH domain, catalytic domain and carboxyl terminal regulator domain. The PH domain of PKB is crucial to the activation of kinase. In order to investigate the function and the structure function relationship of PKB, the cDNA coding fragment of PKB PH domain was amplified from human dental pulp mRNA by RT PCR and cloned into pMD18 T vector to analyze the sequence. The result showed that DNA sequence of cloned human PKB PH domain was consistent with that reported previously. To express PKB PH domain, the cDNA was subcloned into expression vector pRSET A which was then transformed into E.coli BL21(DE3) pLysS, and the strain highly expressing soluble 6His PKB PH domain in minimal medium was obtained. The fusion protein was purified by Ni 2+ NTA agarose beads. The secondary structure of the purified 6His PKB PH domain fusion protein was analysed by circular dichroism. The results indicated that the PH domain was composed of α helix 1 7%,β pleated sheet 80 5% and radom coli 17 8%.
