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Vacuolar Sorting Determinants Within a Plant Storage Protein Trimer Act Cumulatively
Author(s) -
Holkeri Heidi,
Vitale Alessandro
Publication year - 2001
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1034/j.1600-0854.2001.21008.x
Subject(s) - biology , storage protein , microbiology and biotechnology , trimer , protein targeting , protein sorting signals , secretion , transport protein , transgene , mutant , signal peptide , biochemistry , membrane protein , peptide sequence , gene , dimer , chemistry , membrane , organic chemistry
The mechanism for vacuolar sorting of seed storage proteins is as yet poorly understood and no receptor has been identified to date. The homotrimeric glycoprotein phaseolin, which is the major storage protein of the common bean, requires a transient tetrapeptide at the C‐terminus for its vacuolar sorting. A mutated construct without the tetrapeptide is secreted. We show here that coexpression of wild‐type phaseolin and the mutated, secreted form in transgenic tobacco results in the formation of mixed trimers and partial vacuolar delivery of the mutated polypeptides and partial secretion of wild‐type polypeptides. This indicates that the sorting signal has a cumulative effect within a phaseolin trimer. The result is discussed in the light of the hypothesized mechanisms for vacuolar sorting of seed storage proteins.