hca as described by gaboriaud et al 1987 febs letters 224 149 155 and henrissat et al 1988 biochem j 255 901 905 was performed to investigate possible conformational homology of the polypeptide encoded by clone b1 with other known proteins hca plots were produced from the deduced amino acid sequences of nasturtium xet meri 5 and tomato clone b1 using wordperfect u2122 5 1 macros using a modified 2d representation of an u03b1 helix henrissat et al cited above hydrophobic clusters were encircled by hand aligned manually and hca homology scores calculated similar folding was predicted for all three proteins on the basis of a u201c continuous presence of conserved clusters u201d throughout most of the length of the sequence and b overall hca homology scores for all three comparisons being more than 75 meri 5 v tomato xet clone b1 86 nasturtium xet v tomato xet clone b1 80 meri 5 v nasturtium xet 78 this supports data from primary sequence homology and secondary structure predictions kyte amp doolittle 1982 j mol biol 157 105 132 which suggest that these three proteins are likely to have broadly similar folding and therefore similar function whilst differing in detail it was decided to attempt to express clone b2 in e coli this is described below in example 2 a bamhi recognition sequence was introduced close to.