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PAINE'S PROTEIN
In 1999, CCMB
graduate student Caroline Paine was searching for proteins
that interacted with tuftelin—a structural protein thought
to be involved in the creation of enamel—when she came
across one that bared little resemblance to any previously
known.
Dubbed TIP39kDa,
the protein was found on the surface of ameoblasts, epithelial
cells that lay the foundation for the creation of enamel. Its
location suggested a prominent role in the formation of tooth
enamel.
“Caroline pulled
this protein out, and one of the first things we did was to
produce an antibody against it,” says fellow CCMB researcher
and spouse Michael Paine. “It appeared to be present in high
levels in the developing tooth, particularly in the secretory
ameloblast cells that produce enamel.”
With Caroline
happily at home with the couple’s twin children, Michael
Paine took over as principal investigator in 2000. For the
past three years, Paine and his CCMB research team have worked
to identify the function and determine the subcellular
location of TIP.
While the task has
proven difficult, Paine and his team at CCMB have made
considerable headway. CCMB researcher Xin Wen attached
fluorescent protein tags to TIP that showed the protein
resides in the cell’s nucleus, specifically at sites of RNA
transcription.
TIP was also found
to contain a short peptide region, or motif, that is rich in
glycine residues. Previous investigators have identified that
this particular motif is capable of binding directly to RNA.
“With this
information we felt comfortable that TIP played a role in RNA
transcription and/or RNA processing,” says Paine.
Their findings are
supported by the recent explosion of proteomics projects
fueled by data from the Human Genome Project. According to
Paine, four different proteomic research groups have recently
associated TIP with RNA splicing.
To confirm TIP’s
role as a splicing factor, Paine and colleagues at CCMB intend
to down-regulate TIP in either cultured cells or organs.
Through down-regulation, they will decrease its concentration
within the cell. If Paine is correct, this will compromise all
cellular processes.
“My guess is
that TIP is critical to cell survival,” says Paine.
In the meantime,
CCMB researcher Hong Jun Wang is working to identify other
proteins that interact with TIP. By establishing these
relationships, they hope to further understand the role of
TIP.
Paine’s work was
recently awarded a five-year grant in the amount of $1.8
million by the National Institutes of Health. The funds help
defray the considerable cost of proteomics research.
“It’s been a
tremendous help. I really think this is a very worthwhile
project and I’m happy to receive the support of NIH,” says
Paine. |
