Fig. 2. gnu DNA and deduced protein sequence (EMBL Accession Number AJ557828). The genomic sequence of gnu from an isogenic y; cn bw sp stock (Adams et al., 2000) is shown with the exons in upper case and the predicted amino acid sequence shown below the DNA sequence. The consensus splice sites are in italic and the polyadenylation signal is doubly underlined. The site of the C to T mutation on the gnu chromosome (base 709) is indicated by a solid black box. The ESTs GM10421 and LD12084 begin at bases 141 and 151 respectively (denoted by •). On sequencing gnu from OregonR and from our genomic rescue construct the following polymorphisms were found: 91 TC and 113 GA, 165 extra T in our genomic rescue construct (numbers refer to bases with y; cn bw sp version first and polymorphism second). All of these polymorphisms are in untranslated regions except 324 CA in OregonR which is a silent mutation in the coding sequence. Overall there is no polymorphism in the deduced protein sequence. The residues altered in the production of gnuSTOP (boxed), were 692 CA and 694 AT, resulting in a premature TAG stop codon in place of the lysine at 142 and a SpeI site (ACTAGT).