The enhancement of the extracellular carboxyl-terminal domain of human growth hormone receptor on growth hormone dependent responses of 3T3-F442A cells.

We have expressed the carboxyl-terminal domain (C domain) of the cytokine receptor homologous (CRH) region of human growth hormone receptor (hGHR) as a protein fused with maltose binding protein (MBP) in E. coli. Following proteolytic cleavage by restriction protease factor Xa, the C domain was purified to homogeneity as a monomeric form. The purified C domain appears to be folded properly judged by NMR spectrum and the far-UV circular dichroism (CD) spectrum. The C domain did not exhibit ligand binding activity. However, the C domain enhanced the human growth hormone (hGH) dependent differentiation of preadipose 3T3-F442A cells into adipose cells and the phosphorylation of a 34 kDa membrane protein.