The unc-69 locus encodes a 108-amino-acid protein with a short coiled-coil domain. (a) Genetic and physical maps of chromosome III in the vicinity of the unc-69 locus. unc-69 is close to and left of ced-9. Cosmids and subclones able to rescue the locomotion defect of unc-69(e587) mutants are shown in bold. B: BamHI; H: HindIII; M: MluI; P: PstI; R: EcoRI; S: SacI. Introduction of a frameshift mutation at the BamHI site in the second exon (denoted with an x) abrogated rescue by the minimal PstI-SacI rescuing fragment. Both splice variants, T07A5.6a and T07A5.6b, are contained within this fragment. (b) The UNC-69 protein sequence. The boxed region is predicted to form a coiled-coil domain. Arrows indicate the positions of the three known unc-69 mutations. Additional amino acids encoded by T07A5.6b are shown in italics (see Additional data file 1). (c) Northern-blot analysis of unc-69 revealed a single major transcript of 0.65 kb (arrow).