Protein Targeting and Vesicular Trafficking
Maruyama, Nobuyuki , Leong, Ching Mun , Tatsuhara, Miyuki , Ishimoto, Masao , Utsumi, Shigeru .
Multiple vacuolar sorting determinants exist in soybean 11S globulin.
The sorting determinants of glycinin, a soybean 11S globulin, which mediates protein targeting to the protein storage vacuole (PSV), were investigated in maturing soybean cotyledons by transient expression assays. A C-terminal stretch of 10 amino acids of A1aB1b, a glycinin group I subunit, was sufficient to direct green fluorescent protein (GFP) to the PSV. This peptide may correspond to a C-terminal vacuolar sorting determinant (ctVSD). Since functional inhibition of this putative ctVSD of A1aB1b did not block PSV sorting of A1aB1b, we used the three-dimensional structure of A1aB1b to identify candidates for a sequence-specific determinant (ssVSD). We found that the sequence downstream of disordered region 4 could direct GFP to the PSV and that Ile297 is critical for sorting. However, functional inhibition of the ctVSD, combined with the Ile297Gly mutation did not abolish vacuolar sorting of A1aB1b, suggesting that A1aB1b has a third sorting determinant in addition to ctVSD and ssVSD. A glycinin group II subunit, A3B4, lacked a ctVSD but contained a VSD reminiscent of an ssVSD and an additional sorting determinant.We also demonstrated, by expression of dominant negative mutants of small GTPases and drug treatment experiments, that the trafficking of A1aB1b is COPII vesicle-dependent and wortmannin- and brefeldin A-sensitive.
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1 - Kyoto University, Graduate School of Agriculture, Gokasho, Uji, Kyoto, 611-0011, Japan
2 - National Agricultureal Research Center for Hokkaido Region, Toyohira-ku, Sapporo, Hokkaido, 062, Japan
vacuolar sorting determinant
Protein storage vacuole.
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM