MTG8 proto-oncoprotein interacts with the regulatory subunit of type II cyclic AMP-dependent protein kinase in lymphocytes.

AML1-MTG8 chimeric oncogene is generated in acute myelogenous leukemia with t(8;21), and seems to be responsible for the pathogenesis of the disease. However, the role of MTG8 is ambiguous. Here we found that MTG8 interacted with the regulatory subunit of type II cyclic AMP-dependent protein kinase (PKA RIIalpha). The binding site of MTG8 was NHR3 domain, and that of RIIalpha was the N-terminus for interacting with PKA anchoring proteins (AKAPs). NHR3 contains a putative alpha-amphipathic helix which is characteristic in binding of AKAPs with RII. Indirect immunofluorescence microscopy showed that MTG8 and RIIalpha were overlapped at the centrosome-Golgi area in lymphocytes. These findings suggest that MTG8 may function as an AKAP at the centrosome-Golgi area in lymphocytes.