Organization of the P65 operon and recombinant P24 and P41 alleles thereof. (A) The gene products are indicated below each open reading frame of the P65 operon (3, 17). The horizontal arrow indicates the promoter for the operon, while transposon insertions corresponding to residues 22 and 161 of P41 are shown as inverted solid triangles. P28 is a product of internal translation initiation of the MPN310 transcript in the same reading frame as HMW2; antibodies directed against the C-terminal domain of HMW2 recognize P28 (4). The bracket above MPN310 indicates a region deleted in P28− mutant C1R1 (1, 4). (B) Recombinant MPN311 and MPN312 alleles with or without translational fusion to the EYFP gene were engineered in transposon vector Tn4001cat (7). B, BamHI; E, EcoRI; N, NcoI; R, BsrGI; S, StuI.