Ession of Arf1-C11 or Arf1-C17 were not. Note that the internal deletion found in arf1-26 is loss of residues 167?70, which is just upstream of the C-terminus of Arf1-C 11. We conclude from these results that the C-terminal six residues (176?81) are not essential to any of these activities of Arf1 in yeast cells and that the length of the C-terminus may be shortened by as many as six residues with