Fig. 5. Identification and organization of SCD1 and scd1 alleles. (A) The scd1-1 mutation was mapped to a 65 kb region on BAC F27J15, containing 18 predicted open reading frames. Vertical lines show marker positions with an identifier number below each line and a box indicating the number of recombinants detected by each marker. (B) The intron/exon map of the SCD1 gene (At1g49040) in the forward orientation. Positions of the scd1-1 point mutation and the two T-DNA insertion alleles, scd1-2 and scd1-3 are indicated. Arrows denote the location and orientation of primers P1 through P7 described in Table 1 in the Materials and Methods section. TL, T-DNA left Border. (C) The domain structure of SCD1, with the position of the S131F mutation indicated by an asterisk. The tripartite DENN domain starts at the N terminus of SCD1 and extends for 430 amino acids (Levivier et al., 2001), the eight WD-40 repeats span a 500 amino acid region extending to the C terminus. (D) Location of the scd1-1 (S131F) mutation in an alignment of the DENN sub-motif `F' as identified by hydrophobic cluster analysis (Levivier et al., 2001). The alignment compares the sequence of 6 characterized DENN proteins from various organisms that interact with components of vesicle trafficking and MAPK signaling pathways. Residues shaded in black are identical throughout most of the 43 known and hypothetical proteins identified to date containing DENN domains that are present in the GenBank database. Those shaded in gray are conservative substitutions.