We have previously described a novel putative 47 kDa substrate for the protein kinase Akt (designated AS47) in 3T3-L1 adipocytes. In the present study, we have found by co-immunoprecipitation that AS47 was associated with cyclic nucleotide phosphodiesterase 3B (PDE3B) in lysates of 3T3-L1 adipocytes. The patterns of expression of AS47 and PDE3B upon 3T3-L1 adipocyte differentiation, among mouse tissues, and in adipocytes with and without the transcription factor C/EBP alpha were virtually coincident. Partial knockdown of AS47 in 3T3-L1 adipocytes with shRNA resulted in a similar reduction in PDE3B protein. These results indicate that AS47 exists in a complex with PDE3B in adipocytes and that the amount of AS47 protein regulates the amount of PDE3B. (c) 2006 Elsevier Inc. All rights reserved.