Tyrosine-phosphorylated low density lipoprotein receptor-related protein 1 (Lrp1) associates with the adaptor protein SHC in SRC-transformed cells.
v-Src transforms fibroblasts in vitro and causes tumor formation in the animal by tyrosine phosphorylation of critical cellular substrates. Exactly how v-Src interacts with these substrates remains unknown. One of its substrates, the adaptor protein Shc, is thought to play a crucial role during cellular transformation by v-Src by linking v-Src to Ras. We used Shc proteins with mutations in either the phosphotyrosine binding (PTB) or Src homology 2 domain to determine that phosphorylation of Shc in v-Src-expressing cells depends on the presence of a functional PTB domain. We purified a 100-kDa Shc PTB-binding protein from Src-transformed cells that was identified as the beta chain of the low density lipoprotein receptor-related protein LRP1. LRP1 acts as an import receptor for a variety of proteins and is involved in clearance of the beta-amyloid precursor protein. This study shows that LRP1 is tyrosine-phosphorylated in v-Src-transformed cells and that tyrosine-phosphorylated LRP1 binds in vivo and in vitro to Shc. The association between Shc and LRP1 may provide a mechanism for recruitment of Shc to the plasma membrane where it is phosphorylated by v-Src. It is at the membrane that Shc is thought to be involved in Ras activation. These observations further suggest that LRP1 could function as a signaling receptor and may provide new avenues to investigate its possible role during embryonal development and the onset of Alzheimer's disease.
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0359, USA.
H
H
Barnes
B
B
Larsen
M
M
Tyers
P
P
van Der Geer
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000544:Alzheimer Disease / Q000378:metabolism; D000595:Amino Acid Sequence; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002461:Cell Line, Transformed; D002462:Cell Membrane / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D013058:Mass Spectrometry; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D015688:Oncogene Protein pp60(v-src) / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D016564:Amyloid beta-Protein Precursor; D018076:DNA, Complementary; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D011506:Proteins; D011971:Receptors, Immunologic; D011993:Recombinant Fusion Proteins; D055765:Shc Signaling Adaptor Proteins; D014443:Tyrosine; D005982:Glutathione Transferase; D015688:Oncogene Protein pp60(v-src); D018631:ras Proteins