cDNA cloning and deduced amino acid sequences of three storage proteins inthe common cutworm, Spodoptera litura (Lepidoptera : Noctuidae)

Three storage proteins, hexamerins of 80-90 kDa subunits, have been purifie d and characterized from the common cutworm, Spodoptera litura. We have clo ned the cDNAs of these storage proteins by immunoscreening and rapid amplif ication of cDNA ends (RACE). The deduced amino acid sequence of SL-1, a bas ic protein containing 7.7% methionine showed 82.3 and 68.4% identities to t he Trichoplusia ni basic juvenile hormone-suppressible storage protein (8.4 % methionine) and to the Bombyx mori methionine-rich storage protein (11.8% methionine), respectively. The amino acid sequences of alpha and beta subu nits with ca 4% methionine of SL-2, another basic protein, were 84% identic al to that of T. ni basic juvenile hormone-suppressible storage protein wit h moderate methionine content (5.3%), but showed only 45% identity to SL-1. SL-3, an arylphorin was very similar (54-63% identity) to known other aryl phorins, but differed considerably (31-35% identity) from SL-1 and SL-2 in their amino acid alignments. The most parsimonious tree obtained by systema tic analyses of the sequence alignments of 16 lepidopteran storage proteins demonstrated that three storage proteins of S. litura are clustered into t hree sister groups, although they share extensive similarities throughout t he alignment.