TY - JOUR
T1 - Plasma membrane phospholipid scramblase 1 is enriched in lipid rafts and interacts with the epidermal growth factor receptor
AU - Sun, Jun
AU - Nanjundan, Meera
AU - Pike, Linda J.
AU - Wiedmer, Therese
AU - Sims, Peter J.
PY - 2002/5/21
Y1 - 2002/5/21
N2 - We have identified physical and functional interactions between the epidermal growth factor (EGF) receptor and phospholipid scramblase 1 (PLSCR1), an endofacial plasma membrane protein proposed to affect phospholipid organization. PLSCR1, a palmitoylated protein, was found to partition with the EGF receptor in membrane lipid rafts. Cell stimulation with EGF transiently elevated Tyr-phosphorylation of PLSCR1, peaking at 5 min. Although PLSCR1 is a known substrate of c-Abl [Sun, J., et al. (2001) J. Biol. Chem. 276, 28984-28990], the Ab1 inhibitor STI571 did not substantially affect its EGF-dependent phosphorylation, suggesting PLSCR1 is a substrate of the EGF receptor kinase, or another EGF-activated kinase. Coinciding with phosphorylation, there was a transient increase in physical association of PLSCR1 with both the EGF receptor and the adapter protein Shc, as determined by immunoprecipitation and Western blotting. Confocal immunofluorescence analysis revealed that EGF initiates rapid internalization of both the EGF receptor and PLSCR1, with trafficking into both distinct and common endosomal pools. These data also suggested that whereas the EGF receptor is ultimately degraded, much of the endocytosed PLSCR1 is recycled to the cell surface within 3 h after EGF treatment. Consistent with this interpretation, Western blotting revealed neither ubiquitination nor proteolysis of PLSCR1 under these conditions, whereas the ubiquitination and degradation of the EGF receptor were readily confirmed. Finally, stimulation with EGF was also found to markedly increase the total cellular expression of PLSCR1, suggesting that in addition to its initial interactions with activated EGF receptor, PLSCR1 may also contribute to posttranscriptional effector pathway(s) mediating the cellular response to EGF.
AB - We have identified physical and functional interactions between the epidermal growth factor (EGF) receptor and phospholipid scramblase 1 (PLSCR1), an endofacial plasma membrane protein proposed to affect phospholipid organization. PLSCR1, a palmitoylated protein, was found to partition with the EGF receptor in membrane lipid rafts. Cell stimulation with EGF transiently elevated Tyr-phosphorylation of PLSCR1, peaking at 5 min. Although PLSCR1 is a known substrate of c-Abl [Sun, J., et al. (2001) J. Biol. Chem. 276, 28984-28990], the Ab1 inhibitor STI571 did not substantially affect its EGF-dependent phosphorylation, suggesting PLSCR1 is a substrate of the EGF receptor kinase, or another EGF-activated kinase. Coinciding with phosphorylation, there was a transient increase in physical association of PLSCR1 with both the EGF receptor and the adapter protein Shc, as determined by immunoprecipitation and Western blotting. Confocal immunofluorescence analysis revealed that EGF initiates rapid internalization of both the EGF receptor and PLSCR1, with trafficking into both distinct and common endosomal pools. These data also suggested that whereas the EGF receptor is ultimately degraded, much of the endocytosed PLSCR1 is recycled to the cell surface within 3 h after EGF treatment. Consistent with this interpretation, Western blotting revealed neither ubiquitination nor proteolysis of PLSCR1 under these conditions, whereas the ubiquitination and degradation of the EGF receptor were readily confirmed. Finally, stimulation with EGF was also found to markedly increase the total cellular expression of PLSCR1, suggesting that in addition to its initial interactions with activated EGF receptor, PLSCR1 may also contribute to posttranscriptional effector pathway(s) mediating the cellular response to EGF.
UR - http://www.scopus.com/inward/record.url?scp=0037150099&partnerID=8YFLogxK
U2 - 10.1021/bi025610l
DO - 10.1021/bi025610l
M3 - Article
C2 - 12009895
AN - SCOPUS:0037150099
SN - 0006-2960
VL - 41
SP - 6338
EP - 6345
JO - Biochemistry
JF - Biochemistry
IS - 20
ER -