I have been
on a rotation project in the lab of Dr. D. Nathans, who has received the
Nobel Prize in 1978 for his work on restriction enzymes.
Though I have spent only two month in his lab, I believe it was my richest
scientific experience that had the most profound influence on the development
of my scientific views.
The project
involved in vivo labeling of NIH3T3 cells with P32 and immunoprecipitation
of JunB protein with polyclonal antibodies. I demonstrated that JunB
is phosphorylated on Ser and Thr by doing phosphoaminoacid
analysis. I purified radioactively labeled JunB by SDS PAGE and
cleaved the eluted protein with CnBr.
To find which peptide contained radioactive label I used four antibodies
raised against different parts of JunB protein. The radioactive JunB
peptide found by this approach contained phosphorylation sites similar to
c-Jun protein,
which is a JunB homolog.
Since I have
obtained promising results during my first rotation in Jeff Corden’s lab and
because I was interested more in the understanding of the CTD function, I
left Nathan’s lab to continue my work on the C-terminal domain of RNA polymerase
II.