An early nodulin-like protein accumulates in the sieve element plasma membrane of Arabidopsis
Research output: Contribution to journal › Journal article › Research › peer-review
Membrane proteins within the sieve element-companion cell complex have essential roles in the physiological functioning
of the phloem. The monoclonal antibody line RS6, selected from hybridomas raised against sieve elements isolated from
California shield leaf (Streptanthus tortuosus; Brassicaceae) tissue cultures, recognizes an antigen in the Arabidopsis (Arabidopsis
thaliana) ecotype Columbia that is associated specifically with the plasma membrane of sieve elements, but not companion
cells, and accumulates at the earliest stages of sieve element differentiation. The identity of the RS6 antigen was revealed by
reverse transcription-PCR of Arabidopsis leaf RNA using degenerate primers to be an early nodulin (ENOD)-like protein that
is encoded by the expressed gene At3g20570. Arabidopsis ENOD-like proteins are encoded by a multigene family composed of
several types of structurally related phytocyanins that have a similar overall domain structure of an amino-terminal signal
peptide, plastocyanin-like copper-binding domain, proline/serine-rich domain, and carboxy-terminal hydrophobic domain.
The amino- and carboxy-terminal domains of the 21.5-kD sieve element-specific ENOD are posttranslationally cleaved from
the precursor protein, resulting in a mature peptide of approximately 15 kD that is attached to the sieve element plasma
membrane via a carboxy-terminal glycosylphosphatidylinositol membrane anchor. Many of the Arabidopsis ENOD-like proteins
accumulate in gametophytic tissues, whereas in both floral and vegetative tissues, the sieve element-specific ENOD is
expressed only within the phloem. Members of the ENOD subfamily of the cupredoxin superfamily do not appear to bind
copper and have unknown functions. Phenotypic analysis of homozygous T-DNA insertion mutants for the gene At3g20570
shows minimal alteration in vegetative growth but a significant reduction in the overall reproductive potential.
Original language | English |
---|---|
Journal | Plant Physiology |
Volume | 143 |
Issue number | 4 |
Pages (from-to) | 1576-1589 |
Number of pages | 14 |
ISSN | 0032-0889 |
DOIs | |
Publication status | Published - 2007 |
ID: 8100798