DESIGN, SYNTHESIS, EXPRESSION, AND CHARACTERIZATION OF THE GENES FOR MOUSE FC-GAMMA-RIIB1 AND FC-GAMMA-RIIB2 CYTOPLASMIC REGIONS

The cytoplasmic regions of the mouse low-affinity Fc gamma RII isoform s, mFc gamma RIIb1, and mFc gamma RIIb2, play a key role in signal tra nsduction by mediating different cellular functions. mFc gamma RIIb1 h as a 91-residue cytoplasmic region, whereas mFc gamma RIIb2 has a 47-r esidue cytoplasmic region. Genes encoding the cytoplasmic regions of m Fc gamma RIIb1 (b1-94) and mFc gamma RIIb2 (b2-47) were designed, synt hesized, and expressed as fusion proteins in Escherichia coli. A seque nce-specific protease, thrombin, was used to release the b1-94 peptide , which was purified by using HPLC. The b2-47 peptide was synthesized chemically. CD spectropolarimetry was employed to examine the secondar y structures of b1-94 and b2-47. These studies were conducted in aqueo us solution, in mixtures of water and trifluoroethanol or methanol, an d as a function of temperature. The results indicate that the b1-94 an d b2-47 structures are sensitive functions of the solvent environment, and that nonaqueous solvents induce significant alpha-helical structu re.