During the next year we plan to continue purification of several ribosomal proteins from E. coli in hopes of obtaining single crystals for X-ray crystallographic analysis. Specifically, we shall continue our efforts to cocrystallize proteins L7 and L12 and to improve our yields of protein S1 so that more crystallization conditions can be tested. In addition we will begin to purify other ribosomal proteins beginning with L10 and/or L11. Of necessity, purification and crystallization trials will occupy virtually all of our time until the first promising crystals are found. Although the above work will continue from that point, there will be a shift of emphasis toward characterizing the crystals. Should these crystals seem to be at all suitable for full crystallographic analysis we will try to "fine-tune" the crystallization procedure to give us crystals which are both abundant and long-lived. The next logical step will be two-dimensional screening of heavy atom soaks in anticipation of undertaking a complete three-dimensional structure determination.