"Frontmatter". In: Plant Genomics and Proteomics

S
UMMARY
The development of high-throughput tools to look at the transcriptome and
proteome has made a huge impact on our approach to understanding plant
form and function. The ability to simultaneously measure the level of tran-
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6. F
U N C T I O N A L
G
E N O M I C S
His tag
cDNA
Transfer tagged cDNA
to expression vector for
plant transformation
Expression of tagged protein
Isolation of intact proteins
and protein complexes
His tag
Bound protein complex
Release complex
Separate proteins
Identify
Members of in vivo
protein complex identified
Ni affinity
column
FIGURE 6.9.
Isolation and characterization of in vivo protein complexes. A full-
length cDNA is inserted in frame into a vector that will add a His tag to the protein.
This construct is transformed into a plant under the control of an appropriate pro-
moter. The transgenic plant is grown and the tagged protein extracted under condi-
tions in which the protein complexes remain intact. The complex is isolated by
binding the complex with the tag (in this example the His tag bound to a nickel car-
tridge), released and the components dissociated, and characterized by 2-DE and MS
to identify all the protein components of the complex.

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scription of all the genes will increase our understanding of the coordina-
tion of gene expression at the transcription level. Thus the high-throughput
methodology for expression profiling is a way to focus on the interesting
genes while still being able to have a comprehensive view of gene expres-
sion. The more detailed characterization of the fluctuations of each of these
interesting genes will still need to be done. One method for these extended
studies and for confirmation of the expression profiles is real-time PCR. This
will be useful for the characterization of the detailed dynamics of any
changes in expression. The coupling of the expression profiling data with the
characterization of the protein components of the cell facilitates the under-
standing of the transfer of information from DNA to RNA to proteins. An
additional benefit to these studies will be the detection of those RNAs that
are not immediately, or ever, translated into proteins. The detailed protein
studies will also shed light on the role of protein modification in protein
function. High-throughput metabolomic studies are still in their infancy, but
the addition of these data will help our understanding of the flow of infor-
mation through all of the control points in the cell from genomic sequence
to final product.