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One of several genes coding for the major pea storage protein, legumin, has been completely sequenced. The sequence covers the whole of the transcribed region, plus 5' and 3' untranscribed sequences. The predicted protein sequence starts with a signal peptide and is followed by the legumin alpha polypeptide sequence of 36. 44kd and the beta polypeptide sequence of 20. 19kd . Compared to other legume storage proteins, the alpha and beta polypeptide sequences encoded by this legumin gene, which contain 3 met and 5 cys residues, are relatively rich in the sulphur amino acids. The coding sequence is interrupted by three introns which show boundary sequences typical of higher plant genes. The 5' end of the gene sequence contains a 'TATA box', a ' CAAT box' and a sequence showing some homology to an ' AGGA box'. An extra sequence, identical to the normal polyadenylation signal of the legumin message is seen in the 3' untranscribed region. The structure of the gene and the possible significance of secondary structures in the nascent RNA transcript in affecting the choice of polyadenylation site is discussed.

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Tryptic-peptide profiles and amino acid sequencing of purified pea (Pisum sativum L.) vicilin subunits were used to show that their sequences were interrelated. Comparison with the nucleotide sequence of a cloned vicilin complementary DNA (mRNA) showed that all vicilin subunits could be derived from 50 000-Mr precursors containing up to two sites for post-translational proteolytic cleavage, and allowed these subunits to be located relative to the precursor.

The regulatory functions of Rab proteins in membrane trafficking lie in their ability to perform as molecular switches that oscillate between a GTP- and a GDP-bound conformation. The role of tomato LeRab11a in secretion was analyzed in tobacco protoplasts. Green fluorescent protein (GFP)/red fluorescent protein (RFP)-tagged LeRab11a was localized at the trans-Golgi network (TGN) in vivo. Two serines in the GTP-binding site of the protein were mutagenized, giving rise to the three mutants Rab11S22N, Rab11S27N and Rab11S22/27N. The double mutation reduced secretion of a marker protein, secRGUS (secreted rat beta-glucuronidase), by half, whereas each of the single mutations alone had a much smaller effect, showing that both serines have to be mutated to obtain a dominant negative effect on LeRab11a function. The dominant negative mutant was used to determine whether Rab11 is involved in the pathway(s) regulated by the plasma membrane syntaxins SYP121 and SYP122. Co-expression of either of these GFP-tagged syntaxins with the dominant negative Rab11S22/27N mutant led to the appearance of endosomes, but co-expression of GFP-tagged SYP122 also labeled the endoplasmic reticulum and dotted structures. However, co-expression of Rab11S22/27N with SYP121 dominant negative mutants decreased secretion of secRGUS further compared with the expression of Rab11S22/27N alone, whereas co-expression of Rab11S22/27N with SYP122 had no synergistic effect. With the same essay, the difference between SYP121- and SYP122-dependent secretion was then evidenced. The results suggest that Rab11 regulates anterograde transport from the TGN to the plasma membrane and strongly implicate SYP122, rather than SYP121. The differential effect of LeRab11a supports the possibility that SYP121 and SYP122 drive independent secretory events.