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.
Barnes
H
H
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0359, USA.
Larsen
B
B
Tyers
M
M
van Der Geer
P
P
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