Nm23H1 specifically associates with the guanine nucleotide exchanging
factor Tiam1. (a) 293T cells were transiently
transfected with plasmid encoding myc or HA-tagged nm23H1 together with
the Tiam1 constructs indicated above the lanes. Cells were lysed and
immunoprecipitated (IP) with anti-myc (lanes 1–4) or anti-Tiam1-c
(lanes 5–7), which reacts with epitopes located at the carboxyl
terminus of Tiam1. Bound proteins were immunoblotted (IB) with the
antibodies indicated. Expression of Tiam1 and nm23H1 in individual cell
lysates (total lysate) was confirmed by immunoblotting
(Bottom). (b) 293T cells were transiently
cotransfected with flag-tagged wild type or ΔKpn nm23H1 together with
Tiam1 constructs as indicated. Cell lysates were immunoprecipitated
with anti-flag and immunoblotted with the antibodies indicated (lanes
1–3). HA-tagged wild-type or ΔKpn nm23H1 constructs were transiently
transfected with flag-tagged wild-type or ΔKpn nm23H1 constructs
(lanes 4–6). Immunoprecipitation and immunoblotting were performed as
indicated. Expression of nm23H1 and Tiam1 is shown at the bottom.
(c) 293T cells were transiently transfected with plasmid
encoding myc-tagged nm23H1 together with Tiam1, HA-tagged βPIX, or
Vav1 as indicated. Cell lysates were immunoprecipitated with anti-myc
and immunoblotted sequentially with anti-Tiam1-c and anti-HA
antibodies. (d) Whole brains of adult Institute for
Cancer Research (ICR) mice were lysed and immunoprecipitated with
anti-Tiam1-c antibody, normal rabbit Ig fraction, or
peptide-neutralized anti-Tiam1-c antibody. Precipitants were subjected
to immunoblot with the indicated antibodies. These experiments were
performed at least three times.