STRUCTURAL AND BIOCHEMICAL FEATURES OF THE KV1.3 POTASSIUM CHANNEL - AN AID TO GUIDED DRUG DESIGN

The Kv 1.3 potassium channel in T lymphocytes plays a major role in mi togen-induced activation and is widely recognized as a potential thera peutic target for immunosuppressive agents. Availability of structural information on this important protein would greatly facilitate ration al drug design, However, determination of the atomic structure of memb rane proteins poses overwhelming technical challenges. We have therefo re utilized two complementary approaches to probe the architecture of Ky 1.3. The first uses structurally defined peptides as molecular prob es of the pore region of the channel. These studies reveal the existen ce of a similar to 30 Angstrom wide and similar to 6 Angstrom deep, sa ucer-shaped external vestibule, at the center of which lies the select ivity filter as a shallow depression. The second strategy exploits a v accinia viral system to overexpress the Kv 1.3 protein in mammalian ce lls. We have determined the kinetics of Kv 1.3 protein synthesis and t ransport to the membrane in vaccinia-infected cells, and have purified the Kv 1.3 protein from these cells to near homogeneity. The purified protein in detergent is tetrameric with x-y dimensions of 65 x 65 Ang strom.