Expression of rice lectin is governed by two temporally and spatially regulated mRNAs in developing embryos.

Abstract

Two cDNA clones encoding rice lectin have been isolated and characterized to investigate the expression of rice lectin at the molecular and cellular levels. The two cDNA clones code for an identical 23-kilodalton protein which is processed to the mature polypeptide of 18 kilodaltons by co-translational cleavage of a 2.6-kilodalton signal sequence and selective removal of a 2.7-kilodalton COOH-terminal peptide which contains a potential N-linked glycosylation site. In addition, the mature 18-kilodalton lectin is post-translationally cleaved between residues 94 and 95 to yield polypeptides of 10 kilodaltons and 8 kilodaltons, corresponding to the NH2-and COOH-terminal portions of the mature subunit, respectively. RNA gel blot analysis established that rice lectin is encoded by two mRNA transcripts (0.9 kilobase and 1.1 kilobase). On DNA gel blots, the rice lectin cDNAs hybridize specifically to a single restriction fragment. In situ hybridization showed localization of the 1.1-kilobase rice lectin mRNA in root caps and specific cell layers of the radicle, coleorhiza, scutellum, and coleoptile. RNA gel blot analysis demonstrated that both the 0.9-kilobase and 1.1-kilobase mRNAs are present in developing rice embryos. The two lectin mRNAs are differentially expressed temporally such that the 1.1-kilobase lectin mRNA accumulates to levels twofold higher than the 0.9-kilobase mRNA.

Accumulation of the ZRP3 mRNA in the Root and Coleorhiza of Germinating Maize (Zea mays, Poaceae)

“…Root hairs formed only from the outer epidermal cells; the exposed cells of the inner cells ofthe coleorhiza did not differentiate in this manner. Also consistent with a distinction between the epidermal cells and other cell types of the coleorhiza is the pattern of accumulation of a lectin mRNA of rice (Wilkins and Raikhel, 1989). This mRNA accumulates in many organs of the embryo, particularly in epidermal cells of most organs.…”

Characterization of the wound‐induced metallocarboxypeptidase inhibitor from potato1

“…The N‐terminal region of PCI precursor, however, does not share the common motif (NPIRL/P) present in amino‐terminal extensions of some vacuolar proteins [39]. The implication of the C‐terminal propeptide in vacuolar sorting seems very likely, in view of its hydrophobic character and sequence similarities to other reported vacuolar signal sequences [40]. In fact, this potential role had already been suggested for the C‐terminal extension of the tomato inhibitor [6].…”

Wheat pathogenesis‐related proteins of class 4 have ribonuclease activity

“…Besides, they have been classified as chitinases on the basis of the presence of a chitin binding domain found only in a few of them [1]. Actually, the chitin binding domain has been found also in several lectins and in other chitin‐unrelated proteins [26]. In our opinion, PR4 proteins should not be considered as belonging to the chitinase superfamily but could constitute a distinct protein group.…”