Androgen receptor (AR)-associated coregulator 70 (ARA70) is a cytoplasmic protein that has been characterized to have the ability to induce AR transcriptional activity in response to androgens and anti-androgens in prostate cancer cells. AR has been shown to have an important role in the progression of prostate cancer and in normal male reproductive system development. To elucidate the molecular mechanisms and biological relevance of ARA70 to prostrate cancer using a variety of biochemical analyses, the cDNA encoding full length ARA70 was cloned into pET21b vector. Here. we report the refolding and one-step purification of ARA70 from inclusion bodies over-expressed in Escherichia coli. The protein was purified to homogeneity, yielding similar to60 mg ARA70 from 1 L of terrific broth media. Refolding process of ARA70 was monitored using far-UV CD analysis. (C) 2004 Elsevier Inc. All rights reserved.