Molecular Examination of the Transmembrane Requirements of
the Platelet-derived Growth Factor
Receptor for a Productive
Interaction with the Bovine Papillomavirus E5 Oncoprotein*
Valerie M.
Nappi,
Julia A.
Schaefer, and
Lisa M.
Petti
From the Albany Medical College, Albany, New York 12208
The small transmembrane E5 protein of bovine
papillomavirus (BPV) transforms cells by forming a stable complex with
and activating the platelet-derived growth factor
receptor
(PDGF
R). The E5/PDGF
R interaction is thought to involve specific
physical contacts between the transmembrane domains of the two
proteins. Lys499 at the extracellular juxtamembrane
position and Thr513 within the transmembrane domain of the
PDGF
R are required for the interaction and are predicted to contact
analogously positioned residues in the E5 protein. Here, mutagenic
analysis of the transmembrane region of the PDGF
R was performed to
further characterize the nature of the E5/PDGF
R interaction. We show
that the receptor transmembrane domain, with minimal extracellular and
intracellular sequence, is sufficient for the interaction. In addition,
we provide evidence that the polar nature of Thr513 as well
as its positioning along the transmembrane
-helix is important for
the interaction. We also identify the receptor transmembrane amino
acids Ile506 and Leu520 as additional
requirements for the interaction. Because Lys499,
Thr513, Ile506, and Leu520 all
align along the same face of the predicted PDGF
R transmembrane
-helix, our data support the model that the PDGF
R contacts the E5
protein via multiple amino acids along a single
-helical interface.
*
This work was supported by National Institutes of Health
Grant CA73682.The costs of publication of this
article were defrayed in part by the
payment of page charges. The article
must therefore be hereby marked
"advertisement" in
accordance with 18 U.S.C. Section
1734 solely to indicate this fact.