(A) SCAMP3 is tyrosine phosphorylated in
EGF-stimulated NeoR cells. Serum-starved NeoR cells were either
unstimulated (lanes 1, 3, and 5) or stimulated (lanes 2, 4, and 6) with
100 ng/ml EGF for 30 min, lysed in CHAPS buffer, and immunoprecipitated
with either anti-SCAMP (7C12, lanes 1 and 2), anti-SCAMP3 (3γ, lanes
3 and 4), or a control antibody (9E10, lanes 5 and 6). The
immunoprecipitates were blotted for phosphotyrosine (αP-Tyr, upper
panel) or for SCAMP3 (3γ, lower panel). (B) Reimmunoprecipitation of
SCAMP3. NeoR cells were EGF stimulated for 30 min, lysed in CHAPS
buffer, and immunoprecipitated with anti-SCAMP (7C12). Samples 2, 3,
and 4 were boiled in 1% SDS and reconstituted in CHAPS buffer, and
then reimmunoprecipitated with anti-SCAMP (7C12, lane 2), anti-SCAMP3
(3γ, lane 3), or a control antibody (9E10, lane 4). Samples were
Western blotted for phosphotyrosine and visualized using ECL. (C)
Reimmunoprecipitation of SCAMP1. NeoR cells were stimulated with EGF
for 1 h, lysed in CHAPS buffer, and immunoprecipitated with
anti-SCAMP (7C12, lanes 1–3) or anti-SCAMP1 (1Ω, lanes 4 and 5) in
the first round. Samples 2 and 3 were boiled in SDS and reconstituted
in buffer containing 1% CHAPS, and then subjected to a second round of
immunoprecipitation with either anti-SCAMP1 (1Ω, lane 2) or a control
antibody (anti-transferrin receptor, lane 3). Samples were resolved by
SDS-PAGE, transferred to nitrocellulose, Western blotted with either
anti-phosphotyrosine (lanes 1–4) or anti-SCAMP (lane 5), and
visualized by ECL.