Figure 1.

Gene Structure and Peptide Sequence of the Cell Plate–Specific Callose Synthase (CalS1).

(A) Four fragments of the CalS1 cDNA were amplified by RT-PCR using specific primers (small arrows) and RNA from apical meristems of Arabidopsis seedlings. The cDNA was assembled from the PCR fragments and an EST clone (ATTS5466) through unique restriction enzyme sites. Exons are indicated by solid boxes. The larger arrow indicates the 450-bp promoter region (P_UGT1) of UGT1.

(B) The deduced amino acid sequence of CalS1 contains 16 transmembrane helices (boxed). The region between positions 1499 and 1717 that shares homology with the yeast GNS1 protein is underlined. A G-protein–coupled receptor signature is marked by a dashed line, and an inner membrane protein signature of the “binding protein–dependent transport system” (Saurin et al., 1994) is double underlined. A proline-rich domain near the N terminus is marked by asterisks. An energy transfer protein signature is indicated by open circles, and a possible lipid attachment motif of membrane lipoproteins is indicated by carets. The GenBank accession number for UGT1 is AF237733.