Effect of myrAkt on cell surface GLUT4 and Tbc1d1 phosphorylation.
A, 3T3-L1 adipocytes were co-transfected with the plasmid for
HA-GLUT4-GFP and the plasmids for myrAkt1 with a carboxyl-terminal Myc tag
(Akt) and 3× FLAG-tagged human Tbc1d1 (Tbc) or for the
corresponding empty vectors (AV, TV). Cell surface HA-GLUT4-GFP was
measured as described under “Experimental Procedures.” The values
are the averages ± S.E. for four experiments. The values in each
experiment were normalized to 1.0 for the AV, TV control in the
insulin state. B, immunoblots of the SDS samples of the transfected
cells in A for myrAkt with anti-Myc tag and for Tbc1d1 with anti-FLAG
tag. The 1× load contained 20 μg of protein. The anti-Myc also
cross-reacted with a protein that migrated just below myrAkt, which serves as
a loading control. C, SDS/C12E9 lysates of the transfected cells in
A were immunoprecipitated with anti-FLAG agarose. The
immunoadsorbates were immunoblotted for phosphorylation of Tbc1d1 with the PAS
antibody (upper panel) and for Tbc1d1 with anti-FLAG (lower
panel). A repetition of B and C with a second set of
samples gave similar results.